new OS versions added (#87)

* Update hetzner-debian12-zfs-setup.sh

fix for 
===========remove unused kernels in rescue system=========
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package linux-headers-6.11.3
E: Couldn't find any package by glob 'linux-headers-6.11.3'

* try to fix Configuration file '/etc/issue'

* try to fix mountpoint issue

mountpoint '/mnt/' exists and is not empty
use '-m' option to provide a different default

.github/workflows/shellcheck.yml

@@ -0,0 +1,11 @@
+name: shellcheck
+
+on: push
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Run shellcheck
+      run: ci/run_shellcheck.sh

README.md

@@ -1,6 +1,8 @@
 # zfs-hetzner-vm
 
-Scripts to install Debian 10 or Ubuntu 18 with ZFS root on Hetzner root servers (virtual and dedicated).<br/>
+[![shellcheck](https://github.com/terem42/zfs-hetzner-vm/actions/workflows/shellcheck.yml/badge.svg)](https://github.com/terem42/zfs-hetzner-vm/actions/workflows/shellcheck.yml)
+
+Scripts to install Debian 10, 11, 12, 13 or Ubuntu 18 LTS, 20 LTS, 22 LTS, 24 LTS with ZFS root on Hetzner root servers (virtual and dedicated).
 __WARNING:__ all data on the disk will be destroyed.
 
 ## How to use:
@@ -12,25 +14,64 @@ __WARNING:__ all data on the disk will be destroyed.
 
 Debian 10 minimal setup with SSH server
 
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-debian10-zfs-setup.sh | bash -
 ````
-wget -qO- https://raw.githubusercontent.com/andrey42/zfs-hetzner-vm/master/hetzner-debian10-zfs-setup.sh | bash -
+
+Debian 11 minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-debian11-zfs-setup.sh | bash -
+````
+
+Debian 12 minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-debian12-zfs-setup.sh | bash -
+````
+
+Debian 13 minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-debian13-zfs-setup.sh | bash -
 ````
 
 Ubuntu 18.04 LTS minimal setup with SSH server
 
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-ubuntu18-zfs-setup.sh | bash -
 ````
-wget -qO- https://raw.githubusercontent.com/andrey42/zfs-hetzner-vm/master/hetzner-ubuntu18-zfs-setup.sh | bash -
+
+Ubuntu 20 LTS minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-ubuntu20-zfs-setup.sh | bash -
+````
+
+Ubuntu 22 LTS minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-ubuntu22-zfs-setup.sh | bash -
+````
+
+Ubuntu 24 LTS minimal setup with SSH server
+
+````bash
+wget -qO- https://raw.githubusercontent.com/terem42/zfs-hetzner-vm/master/hetzner-ubuntu24-zfs-setup.sh | bash -
 ````
 
 Answer script questions about desired hostname and ZFS ARC cache size.
 
 To cope with network failures its higly recommended to run the commands above inside screen console, type `man screen` for more info.
 Example of screen utility usage:
-````
-screen -S zfs
+
+````bash
+export LC_ALL=en_US.UTF-8 && screen -S zfs
 ````
 To detach from screen console, hit Ctrl-d then a
 To reattach, type `screen -r zfs`
 
 Upon succesfull run, the script will reboot system, and you will be able to login into it, using the same SSH key you have used within rescue console
 
+Please note that the drives you intend to format can not be in use,
+you can execute `mdadm --stop --scan` before running the script to halt default software raid operations.

ci/run_shellcheck.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+set -o pipefail
+set -o errexit
+set -o nounset
+set -o errtrace
+shopt -s inherit_errexit
+
+# Always download the latest version:
+#
+# - it's fast and stable enough not to worry about it;
+# - the workflow is basically single-person, so there's no risk of a new dev encountering an error found
+#   by a new shellcheck version.
+
+mkdir -p /opt/shellcheck
+
+wget -qO- https://github.com/koalaman/shellcheck/releases/download/stable/shellcheck-stable.linux.x86_64.tar.xz \
+  | tar xJv -O shellcheck-stable/shellcheck \
+  > /opt/shellcheck/shellcheck
+
+chmod +x /opt/shellcheck/shellcheck
+
+/opt/shellcheck/shellcheck --version
+
+grep -lZP '^#!/bin/\w+sh' -R | xargs -0 /opt/shellcheck/shellcheck

hetzner-debian10-zfs-setup.sh

@@ -17,6 +17,8 @@ set -o errexit
 set -o pipefail
 set -o nounset
 
+export TMPDIR=/tmp
+
 # Variables
 v_bpool_name=
 v_bpool_tweaks=
@@ -40,7 +42,7 @@ c_deb_security_repo=http://mirror.hetzner.de/debian/security
 
 c_default_zfs_arc_max_mb=250
 c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
-c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=lz4 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
 c_default_hostname=terem
 c_zfs_mount_dir=/mnt
 c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
@@ -62,7 +64,9 @@ function print_step_info_header {
 ###############################################################################
 # ${FUNCNAME[1]}"
 
-  [[ "${1:-}" != "" ]] && echo -n " $1" || true
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
 
   echo "
 ###############################################################################
@@ -106,7 +110,7 @@ This script will prepare the ZFS pools, then install and configure minimal Debia
 The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
 In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
 '
-  dialog --ascii-lines --msgbox "$dialog_message" 30 100
+  dialog --msgbox "$dialog_message" 30 100
 }
 
 function store_os_distro_information {
@@ -134,20 +138,20 @@ function check_prerequisites {
 
 function initial_load_debian_zed_cache {
   chroot_execute "mkdir /etc/zfs/zfs-list.cache"
-  chroot_execute "touch /etc/zfs/zfs-list.cache/rpool"
-  chroot_execute "ln -s /usr/lib/zfs-linux/zed.d/history_event-zfs-list-cacher.sh /etc/zfs/zed.d/"
+  chroot_execute "touch /etc/zfs/zfs-list.cache/$v_rpool_name"
+  chroot_execute "ln -sf /usr/lib/zfs-linux/zed.d/history_event-zfs-list-cacher.sh /etc/zfs/zed.d/"
 
   chroot_execute "zed -F &"
 
   local success=0
 
-  if [[ ! -e /mnt/etc/zfs/zfs-list.cache/rpool ]] || [[ -e /mnt/etc/zfs/zfs-list.cache/rpool && (( $(ls -l /mnt/etc/zfs/zfs-list.cache/rpool 2> /dev/null | cut -d ' ' -f 5) == 0 )) ]]; then
-    chroot_execute "zfs set canmount=noauto rpool"
+  if [[ ! -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] || [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) == 0 )) ]]; then  
+    chroot_execute "zfs set canmount=noauto $v_rpool_name"
 
     SECONDS=0
 
     while (( SECONDS++ <= 120 )); do
-      if [[ -e /mnt/etc/zfs/zfs-list.cache/rpool ]] && (( "$(ls -l /mnt/etc/zfs/zfs-list.cache/rpool | cut -d ' ' -f 5)" > 0 )); then
+      if [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) > 0 )); then
         success=1
         break
       else
@@ -165,7 +169,7 @@ function initial_load_debian_zed_cache {
 
   chroot_execute "pkill zed"
 
-  sed -Ei 's|/mnt/?|/|g' /mnt/etc/zfs/zfs-list.cache/rpool
+  sed -Ei "s|/$c_zfs_mount_dir/?|/|g" "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name"
 }
 
 function find_suitable_disks {
@@ -208,9 +212,9 @@ LOG
   if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
     local dialog_message='No suitable disks have been found!
 
-If you think this is a bug, please open an issue on https://github.com/andrey42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
 '
-    dialog --ascii-lines --msgbox "$dialog_message" 30 100
+    dialog --msgbox "$dialog_message" 30 100
 
     exit 1
   fi
@@ -239,7 +243,7 @@ function select_disks {
 
 Devices with mounted partitions, cdroms, and removable devices are not displayed!
 "
-    mapfile -t v_selected_disks < <(dialog --ascii-lines --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
 
     if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
       break
@@ -256,7 +260,7 @@ function ask_swap_size {
   local swap_size_invalid_message=
 
   while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
-    v_swap_size=$(dialog --ascii-lines --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
 
     swap_size_invalid_message="Invalid swap size! "
   done
@@ -271,7 +275,7 @@ function ask_free_tail_space {
   local tail_space_invalid_message=
 
   while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
-    v_free_tail_space=$(dialog --ascii-lines --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
 
     tail_space_invalid_message="Invalid size! "
   done
@@ -286,7 +290,7 @@ function ask_zfs_arc_max_size {
   local zfs_arc_max_invalid_message=
 
   while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
-    v_zfs_arc_max_mb=$(dialog --ascii-lines --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
 
     zfs_arc_max_invalid_message="Invalid size! "
   done
@@ -302,14 +306,14 @@ function ask_pool_names {
   local bpool_name_invalid_message=
 
   while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_bpool_name=$(dialog --ascii-lines --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
 
     bpool_name_invalid_message="Invalid pool name! "
   done
   local rpool_name_invalid_message=
 
   while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_rpool_name=$(dialog --ascii-lines --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
 
     rpool_name_invalid_message="Invalid pool name! "
   done
@@ -321,8 +325,8 @@ function ask_pool_tweaks {
   # shellcheck disable=SC2119
   print_step_info_header
 
-  v_bpool_tweaks=$(dialog --ascii-lines --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
-  v_rpool_tweaks=$(dialog --ascii-lines --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
 
   print_variables v_bpool_tweaks v_rpool_tweaks
 }
@@ -337,8 +341,8 @@ function ask_root_password {
   local password_repeat=-
 
   while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
-    v_root_password=$(dialog --ascii-lines --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
-    password_repeat=$(dialog --ascii-lines --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
 
     password_invalid_message="Passphrase empty, or not matching! "
   done
@@ -348,7 +352,7 @@ function ask_root_password {
 function ask_encryption {
   print_step_info_header
 
-  if dialog --ascii-lines --yesno 'Do you want to encrypt the root pool?' 30 100; then
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
     v_encrypt_rpool=1
   fi
   set +x
@@ -356,8 +360,8 @@ function ask_encryption {
     local passphrase_invalid_message=
     local passphrase_repeat=-
     while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
-      v_passphrase=$(dialog --ascii-lines --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
-      passphrase_repeat=$(dialog --ascii-lines --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
 
       passphrase_invalid_message="Passphrase too short, or not matching! "
     done
@@ -368,7 +372,7 @@ function ask_encryption {
 function ask_zfs_experimental {
   print_step_info_header
 
-  if dialog --ascii-lines --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
     v_zfs_experimental=1
   fi
 }
@@ -379,8 +383,8 @@ function ask_hostname {
 
   local hostname_invalid_message=
 
-  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_hostname=$(dialog --ascii-lines --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
 
     hostname_invalid_message="Invalid host name! "
   done
@@ -395,7 +399,7 @@ function determine_kernel_variant {
 }
 
 function chroot_execute {
-  chroot $c_zfs_mount_dir bash -c "$1"
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
 }
 
 function unmount_and_export_fs {
@@ -431,9 +435,8 @@ function unmount_and_export_fs {
   zpools_exported=99
   echo "===========exporting zfs pools============="
   set +e
-  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do
-    zpool export -a 2> /dev/null
-    if [[ $? == 0 ]]; then
+  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do    
+    if zpool export -a 2> /dev/null; then
       zpools_exported=1
       echo "all zfs pools were succesfully exported"
       break;
@@ -450,6 +453,7 @@ function unmount_and_export_fs {
 
 #################### MAIN ################################
 export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
 
 check_prerequisites
 
@@ -490,11 +494,20 @@ for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" |
 done
 
 echo "======= installing zfs on rescue system =========="
-  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
-
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
   apt update
-  apt install --yes -t buster-backports libelf-dev zfs-dkms
-  modprobe zfs
+  export PATH=$PATH:/usr/sbin
   zfs --version
 
 echo "======= partitioning the disk =========="
@@ -506,9 +519,9 @@ echo "======= partitioning the disk =========="
   fi
 
   for selected_disk in "${v_selected_disks[@]}"; do
-    wipefs --all "$selected_disk"
+    wipefs --all --force "$selected_disk"
     sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
-    sgdisk -n2:0:+512M                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
     sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
   done
 
@@ -535,12 +548,16 @@ echo "======= create zfs pools and datasets =========="
     pools_mirror_option=
   fi
 
+# shellcheck disable=SC2086
 zpool create \
   $v_bpool_tweaks -O canmount=off -O devices=off \
+  -o cachefile=/etc/zpool.cache \
   -O mountpoint=/boot -R $c_zfs_mount_dir -f \
   $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
 
+# shellcheck disable=SC2086
 echo -n "$v_passphrase" | zpool create \
+  -o cachefile=/etc/zpool.cache \
   $v_rpool_tweaks \
   "${encryption_options[@]}" \
   -O mountpoint=/ -R $c_zfs_mount_dir -f \
@@ -552,13 +569,11 @@ zfs create -o canmount=off -o mountpoint=none "$v_bpool_name/BOOT"
 zfs create -o canmount=noauto -o mountpoint=/ "$v_rpool_name/ROOT/debian"
 zfs mount "$v_rpool_name/ROOT/debian"
 
-zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/ubuntu"
-zfs mount "$v_bpool_name/BOOT/ubuntu"
+zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/debian"
+zfs mount "$v_bpool_name/BOOT/debian"
 
 zfs create                                 "$v_rpool_name/home"
-zfs create -o mountpoint=/root             "$v_rpool_name/home/root"
 zfs create -o canmount=off                 "$v_rpool_name/var"
-zfs create -o canmount=off                 "$v_rpool_name/var/lib"
 zfs create                                 "$v_rpool_name/var/log"
 zfs create                                 "$v_rpool_name/var/spool"
 
@@ -609,7 +624,7 @@ ff02::2 ip6-allrouters
 ff02::3 ip6-allhosts
 CONF
 
-ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p')
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
 
 cat <<CONF > /mnt/etc/systemd/network/10-eth0.network
 [Match]
@@ -621,9 +636,7 @@ Address=${ip6addr_prefix}:1/64
 Gateway=fe80::1
 CONF
 chroot_execute "systemctl enable systemd-networkd.service"
-
-
-cp /etc/resolv.conf $c_zfs_mount_dir/etc/resolv.conf
+chroot_execute "systemctl enable systemd-resolved.service"
 
 echo "======= preparing the jail for chroot =========="
 for virtual_fs_dir in proc sys dev; do
@@ -698,20 +711,23 @@ echo "======= installing aux packages =========="
 chroot_execute "apt install --yes man wget curl software-properties-common nano htop gnupg"
 
 echo "======= installing zfs packages =========="
-if [[ $v_zfs_experimental == "1" ]]; then
-  chroot_execute "wget -O - https://andrey42.github.io/zfs-ubuntu/apt_pub.gpg | apt-key add -"
-  chroot_execute "add-apt-repository 'deb https://andrey42.github.io/zfs-ubuntu/public zfs-debian-experimental main'"
-  chroot_execute "apt update"
-else
-  chroot_execute "apt install --yes zfs-initramfs zfs-dkms"
-fi
 chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
 
 if [[ $v_zfs_experimental == "1" ]]; then
-  chroot_execute "apt install --yes zfs-initramfs zfs-dkms zfsutils-linux"
-else
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
   chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
+else
+  chroot_execute "apt install --yes -t buster-backports zfs-initramfs zfs-dkms zfsutils-linux"
 fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
 echo "======= installing OpenSSH and network tooling =========="
 chroot_execute "apt install --yes openssh-server net-tools"
 
@@ -726,37 +742,22 @@ chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
 echo "======= set root password =========="
 chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
 
-echo "======= setting up zfs services =========="
-chroot_execute "cat > /etc/systemd/system/zfs-import-bpool.service <<UNIT
-[Unit]
-DefaultDependencies=no
-Before=zfs-import-scan.service
-Before=zfs-import-cache.service
-
-[Service]
-Type=oneshot
-RemainAfterExit=yes
-ExecStartPre=/bin/sh -c '[ -f /etc/zfs/zpool.cache ] && mv /etc/zfs/zpool.cache /etc/zfs/preboot_zpool.cache || true'
-ExecStart=/sbin/zpool import -N -o cachefile=none $v_bpool_name
-ExecStartPost=/bin/sh -c '[ -f /etc/zfs/preboot_zpool.cache ] && mv /etc/zfs/preboot_zpool.cache /etc/zfs/zpool.cache || true'
-
-[Install]
-WantedBy=zfs-import.target
-UNIT"
-
-chroot_execute "systemctl enable zfs-import-bpool.service"
+echo "======= setting up zfs cache =========="
+cp /etc/zpool.cache /mnt/etc/zfs/zpool.cache
 
 echo "========setting up zfs module parameters========"
 chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
 
 echo "======= setting up grub =========="
 chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
-chroot_execute "DEBIAN_FRONTEND=noninteractive apt install --yes grub-pc"
-chroot_execute "grub-install ${v_selected_disks[0]}"
+chroot_execute "apt install --yes grub-pc"
+for disk in ${v_selected_disks[@]}; do
+  chroot_execute "grub-install $disk"
+done
 
 chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
 chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
-chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=rpool/ROOT/debian\"|g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/debian\"|g' /etc/default/grub"
 
 chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
 chroot_execute "sed -i 's/splash//g' /etc/default/grub"
@@ -770,7 +771,8 @@ if [[ $v_encrypt_rpool == "1" ]]; then
   echo "=========set up dropbear=============="
 
   chroot_execute "apt install --yes dropbear-initramfs"
-
+    
+  mkdir -p "$c_zfs_mount_dir/etc/dropbear-initramfs"
   cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/etc/dropbear-initramfs/authorized_keys"
 
   cp "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
@@ -787,18 +789,6 @@ if [[ $v_encrypt_rpool == "1" ]]; then
   rm -rf "$c_zfs_mount_dir/etc/dropbear-initramfs/dropbear_dss_host_key"
 fi 
 
-#cd "$c_zfs_mount_dir/root"
-#wget http://ftp.de.debian.org/debian/pool/main/libt/libtommath/libtommath1_1.1.0-3_amd64.deb
-#wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-bin_2018.76-5_amd64.deb
-#wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-initramfs_2018.76-5_all.deb
-
-#chroot_execute "dpkg -i /root/libtommath1_1.1.0-3_amd64.deb"
-#chroot_execute "dpkg -i /root/dropbear-bin_2018.76-5_amd64.deb"
-#chroot_execute "dpkg -i /root/dropbear-initramfs_2018.76-5_all.deb"
-
-#rm $c_zfs_mount_dir/root/*.deb
-#cd /root
-
 echo "============setup root prompt============"
 cat > "$c_zfs_mount_dir/root/.bashrc" <<CONF
 export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
@@ -809,9 +799,45 @@ CONF
 
 echo "========running packages upgrade==========="
 chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
 
-#echo "===========add static route to initramfs via hook to add default routes due to  initramfs DHCP bug ========="
-# removed
+echo "===========add static route to initramfs via hook to add default routes for Hetzner due to Debian/Ubuntu initramfs DHCP bug ========="
+mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
+cat > "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route" <<'CONF'
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+    echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+
+. /scripts/functions
+# Begin real processing below this line
+
+configure_networking
+
+ip route add 172.31.1.1/255.255.255.255 dev eth0
+ip route add default via 172.31.1.1 dev eth0
+CONF
+
+cat > "$c_zfs_mount_dir/etc/network/interfaces" <<'CONF'
+auto lo
+iface lo inet loopback
+iface lo inet6 loopback
+
+allow-hotplug eth0
+iface eth0 inet dhcp
+iface eth0 inet6 dhcp
+CONF
+
+chmod 755 "$c_zfs_mount_dir/etc/network/interfaces"
 
 echo "======= update initramfs =========="
 chroot_execute "update-initramfs -u -k all"
@@ -821,14 +847,14 @@ chroot_execute "update-grub"
 
 echo "======= setting up zed =========="
 if [[ $v_zfs_experimental == "1" ]]; then
-  chroot_execute "zfs set canmount=noauto rpool"
+  chroot_execute "zfs set canmount=noauto $v_rpool_name"
 else
   initial_load_debian_zed_cache
 fi
 
 echo "======= setting mountpoints =========="
-chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/ubuntu"
-chroot_execute "echo $v_bpool_name/BOOT/ubuntu /boot zfs nodev,relatime,x-systemd.requires=zfs-import-bpool.service 0 0 > /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/debian"
+chroot_execute "echo $v_bpool_name/BOOT/debian /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
 
 chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
 chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
@@ -840,7 +866,9 @@ chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
 chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
 
 echo "========= add swap, if defined"
-[[ $v_swap_size -gt 0 ]] && chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab" || true
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
 chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
 
 echo "======= unmounting filesystems and zfs pools =========="

hetzner-debian11-zfs-setup.sh

@@ -0,0 +1,876 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Debian 11 with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, set it OS to linux64, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname, ZFS ARC cache size et cetera
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -o errexit
+set -o pipefail
+set -o nounset
+
+export TMPDIR=/tmp
+
+# Variables
+v_bpool_name=
+v_bpool_tweaks=
+v_rpool_name=
+v_rpool_tweaks=
+declare -a v_selected_disks
+v_swap_size=                 # integer
+v_free_tail_space=           # integer
+v_hostname=
+v_kernel_variant=
+v_zfs_arc_max_mb=
+v_root_password=
+v_encrypt_rpool=             # 0=false, 1=true
+v_passphrase=
+v_zfs_experimental=
+v_suitable_disks=()
+
+# Constants
+c_deb_packages_repo=https://mirror.hetzner.com/debian/packages
+c_deb_security_repo=https://mirror.hetzner.com/debian/security
+
+c_default_zfs_arc_max_mb=250
+c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_hostname=terem
+c_zfs_mount_dir=/mnt
+c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
+c_install_log=$c_log_dir/install.log
+c_lsb_release_log=$c_log_dir/lsb_release.log
+c_disks_log=$c_log_dir/disks.log
+
+function activate_debug {
+  mkdir -p "$c_log_dir"
+
+  exec 5> "$c_install_log"
+  BASH_XTRACEFD="5"
+  set -x
+}
+
+# shellcheck disable=SC2120
+function print_step_info_header {
+  echo -n "
+###############################################################################
+# ${FUNCNAME[1]}"
+
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
+
+
+  echo "
+###############################################################################
+"
+}
+
+function print_variables {
+  for variable_name in "$@"; do
+    declare -n variable_reference="$variable_name"
+
+    echo -n "$variable_name:"
+
+    case "$(declare -p "$variable_name")" in
+    "declare -a"* )
+      for entry in "${variable_reference[@]}"; do
+        echo -n " \"$entry\""
+      done
+      ;;
+    "declare -A"* )
+      for key in "${!variable_reference[@]}"; do
+        echo -n " $key=\"${variable_reference[$key]}\""
+      done
+      ;;
+    * )
+      echo -n " $variable_reference"
+      ;;
+    esac
+
+    echo
+  done
+
+  echo
+}
+
+function display_intro_banner {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local dialog_message='Hello!
+This script will prepare the ZFS pools, then install and configure minimal Debian 11 with ZFS root on Hetzner hosting VPS instance
+The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
+In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
+'
+  dialog --msgbox "$dialog_message" 30 100
+}
+
+function store_os_distro_information {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  lsb_release --all > "$c_lsb_release_log"
+}
+
+function check_prerequisites {
+  # shellcheck disable=SC2119
+  print_step_info_header
+  if [[ $(id -u) -ne 0 ]]; then
+    echo 'This script must be run with administrative privileges!'
+    exit 1
+  fi
+  if [[ ! -r /root/.ssh/authorized_keys ]]; then
+    echo "SSH pubkey file is absent, please add it to the rescue system setting, then reboot into rescue system and run the script"
+    exit 1
+  fi
+  if ! dpkg-query --showformat="\${Status}" -W dialog 2> /dev/null | grep -q "install ok installed"; then
+    apt install --yes dialog
+  fi
+}
+
+function initial_load_debian_zed_cache {
+  chroot_execute "mkdir /etc/zfs/zfs-list.cache"
+  chroot_execute "touch /etc/zfs/zfs-list.cache/$v_rpool_name"
+  chroot_execute "ln -sf /usr/lib/zfs-linux/zed.d/history_event-zfs-list-cacher.sh /etc/zfs/zed.d/"
+
+  chroot_execute "zed -F &"
+
+  local success=0
+
+  if [[ ! -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] || [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) == 0 )) ]]; then  
+    chroot_execute "zfs set canmount=noauto $v_rpool_name"
+
+    SECONDS=0
+
+    while (( SECONDS++ <= 120 )); do
+      if [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) > 0 )); then
+        success=1
+        break
+      else
+        sleep 1
+      fi
+    done
+  else
+    success=1
+  fi
+
+  if (( success != 1 )); then
+    echo "Fatal zed daemon error: the ZFS cache hasn't been updated by ZED!"
+    exit 1
+  fi
+
+  chroot_execute "pkill zed"
+
+  sed -Ei "s|/$c_zfs_mount_dir/?|/|g" "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name"
+}
+
+function find_suitable_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  udevadm trigger
+
+  # shellcheck disable=SC2012
+  ls -l /dev/disk/by-id | tail -n +2 | perl -lane 'print "@F[8..10]"' > "$c_disks_log"
+
+  local candidate_disk_ids
+  local mounted_devices
+
+  candidate_disk_ids=$(find /dev/disk/by-id -regextype awk -regex '.+/(ata|nvme|scsi)-.+' -not -regex '.+-part[0-9]+$' | sort)
+  mounted_devices="$(df | awk 'BEGIN {getline} {print $1}' | xargs -n 1 lsblk -no pkname 2> /dev/null | sort -u || true)"
+
+  while read -r disk_id || [[ -n "$disk_id" ]]; do
+    local device_info
+
+    device_info="$(udevadm info --query=property "$(readlink -f "$disk_id")")"
+    block_device_basename="$(basename "$(readlink -f "$disk_id")")"
+
+    if ! grep -q '^ID_TYPE=cd$' <<< "$device_info"; then
+      if ! grep -q "^$block_device_basename\$" <<< "$mounted_devices"; then
+        v_suitable_disks+=("$disk_id")
+      fi
+    fi
+
+    cat >> "$c_disks_log" << LOG
+
+## DEVICE: $disk_id ################################
+
+$(udevadm info --query=property "$(readlink -f "$disk_id")")
+
+LOG
+
+  done < <(echo -n "$candidate_disk_ids")
+
+  if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
+    local dialog_message='No suitable disks have been found!
+
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+'
+    dialog --msgbox "$dialog_message" 30 100
+
+    exit 1
+  fi
+
+  print_variables v_suitable_disks
+}
+
+function select_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  while true; do
+    local menu_entries_option=()
+
+    if [[ ${#v_suitable_disks[@]} -eq 1 ]]; then
+      local disk_selection_status=ON
+    else
+      local disk_selection_status=OFF
+    fi
+
+    for disk_id in "${v_suitable_disks[@]}"; do
+      menu_entries_option+=("$disk_id" "($block_device_basename)" "$disk_selection_status")
+    done
+
+    local dialog_message="Select the ZFS devices (multiple selections will be in mirror).
+
+Devices with mounted partitions, cdroms, and removable devices are not displayed!
+"
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+
+    if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
+      break
+    fi
+  done
+
+  print_variables v_selected_disks
+}
+
+function ask_swap_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local swap_size_invalid_message=
+
+  while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+
+    swap_size_invalid_message="Invalid swap size! "
+  done
+
+  print_variables v_swap_size
+}
+
+function ask_free_tail_space {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local tail_space_invalid_message=
+
+  while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+
+    tail_space_invalid_message="Invalid size! "
+  done
+
+  print_variables v_free_tail_space
+}
+
+function ask_zfs_arc_max_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local zfs_arc_max_invalid_message=
+
+  while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+
+    zfs_arc_max_invalid_message="Invalid size! "
+  done
+
+  print_variables v_zfs_arc_max_mb
+}
+
+
+function ask_pool_names {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local bpool_name_invalid_message=
+
+  while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+
+    bpool_name_invalid_message="Invalid pool name! "
+  done
+  local rpool_name_invalid_message=
+
+  while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+
+    rpool_name_invalid_message="Invalid pool name! "
+  done
+
+  print_variables v_bpool_name v_rpool_name
+}
+
+function ask_pool_tweaks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+
+  print_variables v_bpool_tweaks v_rpool_tweaks
+}
+
+
+function ask_root_password {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  set +x
+  local password_invalid_message=
+  local password_repeat=-
+
+  while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+
+    password_invalid_message="Passphrase empty, or not matching! "
+  done
+  set -x
+}
+
+function ask_encryption {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
+    v_encrypt_rpool=1
+  fi
+  set +x
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    local passphrase_invalid_message=
+    local passphrase_repeat=-
+    while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+
+      passphrase_invalid_message="Passphrase too short, or not matching! "
+    done
+  fi
+  set -x
+}
+
+function ask_zfs_experimental {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+    v_zfs_experimental=1
+  fi
+}
+
+function ask_hostname {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local hostname_invalid_message=
+
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+
+    hostname_invalid_message="Invalid host name! "
+  done
+
+  print_variables v_hostname
+}
+
+function determine_kernel_variant {
+  if dmidecode | grep -q vServer; then
+    v_kernel_variant="-cloud"
+  fi
+}
+
+function chroot_execute {
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
+}
+
+function unmount_and_export_fs {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  for virtual_fs_dir in dev sys proc; do
+    umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+  done
+
+  local max_unmount_wait=5
+  echo -n "Waiting for virtual filesystems to unmount "
+
+  SECONDS=0
+
+  for virtual_fs_dir in dev sys proc; do
+    while mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir" && [[ $SECONDS -lt $max_unmount_wait ]]; do
+      sleep 0.5
+      echo -n .
+    done
+  done
+
+  echo
+
+  for virtual_fs_dir in dev sys proc; do
+    if mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir"; then
+      echo "Re-issuing umount for $c_zfs_mount_dir/$virtual_fs_dir"
+      umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+    fi
+  done
+
+  SECONDS=0
+  zpools_exported=99
+  echo "===========exporting zfs pools============="
+  set +e
+  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do    
+    if zpool export -a 2> /dev/null; then
+      zpools_exported=1
+      echo "all zfs pools were succesfully exported"
+      break;
+    else
+      sleep 1
+     fi
+  done
+  set -e
+  if (( zpools_exported != 1 )); then
+    echo "failed to export zfs pools"
+    exit 1
+  fi
+}
+
+#################### MAIN ################################
+export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
+
+check_prerequisites
+
+activate_debug
+
+display_intro_banner
+
+find_suitable_disks
+
+select_disks
+
+ask_swap_size
+
+ask_free_tail_space
+
+ask_pool_names
+
+ask_pool_tweaks
+
+ask_encryption
+
+ask_zfs_arc_max_size
+
+ask_zfs_experimental
+
+ask_root_password
+
+ask_hostname
+
+determine_kernel_variant
+
+clear
+
+echo "===========remove unused kernels in rescue system========="
+for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" | cut -s -d "/" -f 4); do
+  apt purge --yes "linux-headers-$kver"
+  apt purge --yes "linux-image-$kver"
+done
+
+echo "======= installing zfs on rescue system =========="
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
+  apt update
+  export PATH=$PATH:/usr/sbin
+  zfs --version
+
+echo "======= partitioning the disk =========="
+
+  if [[ $v_free_tail_space -eq 0 ]]; then
+    tail_space_parameter=0
+  else
+    tail_space_parameter="-${v_free_tail_space}G"
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    wipefs --all --force "$selected_disk"
+    sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
+  done
+
+  udevadm settle
+
+echo "======= create zfs pools and datasets =========="
+
+  encryption_options=()
+  rpool_disks_partitions=()
+  bpool_disks_partitions=()
+
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    encryption_options=(-O "encryption=aes-256-gcm" -O "keylocation=prompt" -O "keyformat=passphrase")
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    rpool_disks_partitions+=("${selected_disk}-part3")
+    bpool_disks_partitions+=("${selected_disk}-part2")
+  done
+
+  if [[ ${#v_selected_disks[@]} -gt 1 ]]; then
+    pools_mirror_option=mirror
+  else
+    pools_mirror_option=
+  fi
+
+# shellcheck disable=SC2086
+zpool create \
+  $v_bpool_tweaks -O canmount=off -O devices=off \
+  -o cachefile=/etc/zpool.cache \
+  -O mountpoint=/boot -R $c_zfs_mount_dir -f \
+  $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
+
+# shellcheck disable=SC2086
+echo -n "$v_passphrase" | zpool create \
+  $v_rpool_tweaks \
+  -o cachefile=/etc/zpool.cache \
+  "${encryption_options[@]}" \
+  -O mountpoint=/ -R $c_zfs_mount_dir -f \
+  $v_rpool_name $pools_mirror_option "${rpool_disks_partitions[@]}"
+
+zfs create -o canmount=off -o mountpoint=none "$v_rpool_name/ROOT"
+zfs create -o canmount=off -o mountpoint=none "$v_bpool_name/BOOT"
+
+zfs create -o canmount=noauto -o mountpoint=/ "$v_rpool_name/ROOT/debian"
+zfs mount "$v_rpool_name/ROOT/debian"
+
+zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/debian"
+zfs mount "$v_bpool_name/BOOT/debian"
+
+zfs create                                 "$v_rpool_name/home"
+zfs create -o canmount=off                 "$v_rpool_name/var"
+zfs create                                 "$v_rpool_name/var/log"
+zfs create                                 "$v_rpool_name/var/spool"
+
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/cache"
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/tmp"
+chmod 1777 "$c_zfs_mount_dir/var/tmp"
+
+zfs create                                 "$v_rpool_name/srv"
+
+zfs create -o canmount=off                 "$v_rpool_name/usr"
+zfs create                                 "$v_rpool_name/usr/local"
+
+zfs create                                 "$v_rpool_name/var/mail"
+
+zfs create -o com.sun:auto-snapshot=false -o canmount=on -o mountpoint=/tmp "$v_rpool_name/tmp"
+chmod 1777 "$c_zfs_mount_dir/tmp"
+
+if [[ $v_swap_size -gt 0 ]]; then
+  zfs create \
+    -V "${v_swap_size}G" -b "$(getconf PAGESIZE)" \
+    -o compression=zle -o logbias=throughput -o sync=always -o primarycache=metadata -o secondarycache=none -o com.sun:auto-snapshot=false \
+    "$v_rpool_name/swap"
+
+  udevadm settle
+
+  mkswap -f "/dev/zvol/$v_rpool_name/swap"
+fi
+
+echo "======= setting up initial system packages =========="
+debootstrap --arch=amd64 bullseye "$c_zfs_mount_dir" "$c_deb_packages_repo"
+
+zfs set devices=off "$v_rpool_name"
+
+echo "======= setting up the network =========="
+
+echo "$v_hostname" > $c_zfs_mount_dir/etc/hostname
+
+cat > "$c_zfs_mount_dir/etc/hosts" <<CONF
+127.0.1.1 ${v_hostname}
+127.0.0.1 localhost
+
+# The following lines are desirable for IPv6 capable hosts
+::1 ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+CONF
+
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
+
+cat <<CONF > /mnt/etc/systemd/network/10-eth0.network
+[Match]
+Name=eth0
+
+[Network]
+DHCP=ipv4
+Address=${ip6addr_prefix}:1/64
+Gateway=fe80::1
+CONF
+chroot_execute "systemctl enable systemd-networkd.service"
+chroot_execute "systemctl enable systemd-resolved.service"
+
+#cp /etc/resolv.conf $c_zfs_mount_dir/etc/resolv.conf
+
+echo "======= preparing the jail for chroot =========="
+for virtual_fs_dir in proc sys dev; do
+  mount --rbind "/$virtual_fs_dir" "$c_zfs_mount_dir/$virtual_fs_dir"
+done
+
+echo "======= setting apt repos =========="
+cat > "$c_zfs_mount_dir/etc/apt/sources.list" <<CONF
+deb $c_deb_packages_repo bullseye main contrib non-free
+deb $c_deb_packages_repo bullseye-updates main contrib non-free
+deb $c_deb_security_repo bullseye-security main contrib non-free
+deb $c_deb_packages_repo bullseye-backports main contrib non-free
+CONF
+
+chroot_execute "apt update"
+
+echo "======= setting locale, console and language =========="
+chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils"
+sed -i 's/# en_US.UTF-8/en_US.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_AT.UTF-8/de_AT.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_DE.UTF-8/de_DE.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+
+chroot_execute 'cat <<CONF | debconf-set-selections
+locales locales/default_environment_locale      select  en_US.UTF-8
+keyboard-configuration  keyboard-configuration/store_defaults_in_debconf_db     boolean true
+keyboard-configuration  keyboard-configuration/variant  select  German
+keyboard-configuration  keyboard-configuration/unsupported_layout       boolean true
+keyboard-configuration  keyboard-configuration/modelcode        string  pc105
+keyboard-configuration  keyboard-configuration/unsupported_config_layout        boolean true
+keyboard-configuration  keyboard-configuration/layout   select  German
+keyboard-configuration  keyboard-configuration/layoutcode       string  de
+keyboard-configuration  keyboard-configuration/optionscode      string
+keyboard-configuration  keyboard-configuration/toggle   select  No toggling
+keyboard-configuration  keyboard-configuration/xkb-keymap       select  de
+keyboard-configuration  keyboard-configuration/switch   select  No temporary switch
+keyboard-configuration  keyboard-configuration/unsupported_config_options       boolean true
+keyboard-configuration  keyboard-configuration/ctrl_alt_bksp    boolean false
+keyboard-configuration  keyboard-configuration/variantcode      string
+keyboard-configuration  keyboard-configuration/model    select  Generic 105-key PC (intl.)
+keyboard-configuration  keyboard-configuration/altgr    select  The default for the keyboard layout
+keyboard-configuration  keyboard-configuration/compose  select  No compose key
+keyboard-configuration  keyboard-configuration/unsupported_options      boolean true
+console-setup   console-setup/fontsize-fb47     select  8x16
+console-setup   console-setup/store_defaults_in_debconf_db      boolean true
+console-setup   console-setup/codeset47 select  # Latin1 and Latin5 - western Europe and Turkic languages
+console-setup   console-setup/fontface47        select  Fixed
+console-setup   console-setup/fontsize  string  8x16
+console-setup   console-setup/charmap47 select  UTF-8
+console-setup   console-setup/fontsize-text47   select  8x16
+console-setup   console-setup/codesetcode       string  Lat15
+tzdata tzdata/Areas select Europe
+tzdata tzdata/Zones/Europe select Vienna
+grub-pc grub-pc/install_devices_empty   boolean true
+CONF'
+
+chroot_execute "dpkg-reconfigure locales -f noninteractive"
+echo -e "LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8\n" >> "$c_zfs_mount_dir/etc/environment"
+chroot_execute "apt install -qq --yes keyboard-configuration console-setup"
+chroot_execute "dpkg-reconfigure keyboard-configuration -f noninteractive"
+chroot_execute "dpkg-reconfigure console-setup -f noninteractive"
+chroot_execute "setupcon"
+
+chroot_execute "rm -f /etc/localtime /etc/timezone"
+chroot_execute "dpkg-reconfigure tzdata -f noninteractive "
+
+echo "======= installing latest kernel============="
+chroot_execute "apt install --yes linux-image${v_kernel_variant}-amd64 linux-headers${v_kernel_variant}-amd64"
+
+echo "======= installing aux packages =========="
+chroot_execute "apt install --yes man wget curl software-properties-common nano htop gnupg"
+
+echo "======= installing zfs packages =========="
+chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
+
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
+  chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
+else
+  chroot_execute "apt install -t bullseye-backports --yes zfs-initramfs zfs-dkms zfsutils-linux"
+fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
+echo "======= installing OpenSSH and network tooling =========="
+chroot_execute "apt install --yes openssh-server net-tools"
+
+echo "======= setup OpenSSH  =========="
+mkdir -p "$c_zfs_mount_dir/root/.ssh/"
+cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/root/.ssh/authorized_keys"
+sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+chroot_execute "rm /etc/ssh/ssh_host_*"
+chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
+
+echo "======= set root password =========="
+chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
+
+echo "======= setting up zfs cache =========="
+
+cp /etc/zpool.cache /mnt/etc/zfs/zpool.cache
+
+echo "========setting up zfs module parameters========"
+chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
+
+echo "======= setting up grub =========="
+chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
+chroot_execute "apt install --yes grub-legacy"
+chroot_execute "apt install --yes grub-pc"
+for disk in ${v_selected_disks[@]}; do
+  chroot_execute "grub-install --recheck $disk"
+done
+
+chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/debian\"|g' /etc/default/grub"
+
+chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
+chroot_execute "sed -i 's/splash//g' /etc/default/grub"
+chroot_execute "echo 'GRUB_DISABLE_OS_PROBER=true'   >> /etc/default/grub"
+
+for ((i = 1; i < ${#v_selected_disks[@]}; i++)); do
+  dd if="${v_selected_disks[0]}-part1" of="${v_selected_disks[i]}-part1"
+done
+
+if [[ $v_encrypt_rpool == "1" ]]; then
+  echo "=========set up dropbear=============="
+
+  chroot_execute "apt install --yes dropbear-initramfs"
+  
+  mkdir -p "$c_zfs_mount_dir/etc/dropbear/initramfs"
+  cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/etc/dropbear/initramfs/authorized_keys"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_rsa_key_temp /etc/dropbear/initramfs/dropbear_rsa_host_key"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_ecdsa_key_temp /etc/dropbear/initramfs/dropbear_ecdsa_host_key"
+  chroot_execute "rm -rf /etc/ssh/ssh_host_ecdsa_key_temp"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+
+  rm -rf "$c_zfs_mount_dir/etc/dropbear/initramfs/dropbear_dss_host_key"
+fi
+
+echo "============setup root prompt============"
+cat > "$c_zfs_mount_dir/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+
+echo "========running packages upgrade==========="
+chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
+
+echo "===========add static route to initramfs via hook to add default routes for Hetzner due to Debian/Ubuntu initramfs DHCP bug ========="
+mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
+cat > "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route" <<'CONF'
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+    echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+
+. /scripts/functions
+# Begin real processing below this line
+
+configure_networking
+
+ip route add 172.31.1.1/255.255.255.255 dev eth0
+ip route add default via 172.31.1.1 dev eth0
+CONF
+
+chmod 755 "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route"
+
+chmod 755 "$c_zfs_mount_dir/etc/network/interfaces"
+
+echo "======= update initramfs =========="
+chroot_execute "update-initramfs -u -k all"
+
+echo "======= update grub =========="
+chroot_execute "update-grub"
+
+echo "======= setting up zed =========="
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "zfs set canmount=noauto $v_rpool_name"
+else
+  initial_load_debian_zed_cache
+fi
+
+echo "======= setting mountpoints =========="
+chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/debian"
+chroot_execute "echo $v_bpool_name/BOOT/debian /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
+
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
+chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/spool"
+chroot_execute "echo $v_rpool_name/var/spool /var/spool zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/tmp"
+chroot_execute "echo $v_rpool_name/var/tmp /var/tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
+chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+
+echo "========= add swap, if defined"
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
+
+chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
+
+echo "======= unmounting filesystems and zfs pools =========="
+unmount_and_export_fs
+
+echo "======== setup complete, rebooting ==============="
+reboot

hetzner-debian12-zfs-setup.sh

@@ -0,0 +1,916 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Debian 12 with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, set it OS to linux64, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname, ZFS ARC cache size et cetera
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -o errexit
+set -o pipefail
+set -o nounset
+
+export TMPDIR=/tmp
+export DEBIAN_FRONTEND=noninteractive
+
+# Variables
+v_bpool_name=
+v_bpool_tweaks=
+v_rpool_name=
+v_rpool_tweaks=
+declare -a v_selected_disks
+v_swap_size=                 # integer
+v_free_tail_space=           # integer
+v_hostname=
+v_kernel_variant=
+v_zfs_arc_max_mb=
+v_root_password=
+v_encrypt_rpool=             # 0=false, 1=true
+v_passphrase=
+v_zfs_experimental=
+v_suitable_disks=()
+
+# Constants
+c_deb_packages_repo=https://deb.debian.org/debian
+c_deb_security_repo=https://deb.debian.org/debian-security
+
+c_default_zfs_arc_max_mb=250
+c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_hostname=terem
+c_zfs_mount_dir=/mnt
+c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
+c_install_log=$c_log_dir/install.log
+c_lsb_release_log=$c_log_dir/lsb_release.log
+c_disks_log=$c_log_dir/disks.log
+c_efimode_enabled="$(if [[ -d /sys/firmware/efi/efivars ]]; then echo 1; else echo 0; fi)"
+
+function activate_debug {
+  mkdir -p "$c_log_dir"
+
+  exec 5> "$c_install_log"
+  BASH_XTRACEFD="5"
+  set -x
+}
+
+# shellcheck disable=SC2120
+function print_step_info_header {
+  echo -n "
+###############################################################################
+# ${FUNCNAME[1]}"
+
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
+
+
+  echo "
+###############################################################################
+"
+}
+
+function print_variables {
+  for variable_name in "$@"; do
+    declare -n variable_reference="$variable_name"
+
+    echo -n "$variable_name:"
+
+    case "$(declare -p "$variable_name")" in
+    "declare -a"* )
+      for entry in "${variable_reference[@]}"; do
+        echo -n " \"$entry\""
+      done
+      ;;
+    "declare -A"* )
+      for key in "${!variable_reference[@]}"; do
+        echo -n " $key=\"${variable_reference[$key]}\""
+      done
+      ;;
+    * )
+      echo -n " $variable_reference"
+      ;;
+    esac
+
+    echo
+  done
+
+  echo
+}
+
+function display_intro_banner {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local dialog_message='Hello!
+This script will prepare the ZFS pools, then install and configure minimal Debian 12 with ZFS root on Hetzner hosting VPS instance
+The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
+In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
+'
+  dialog --msgbox "$dialog_message" 30 100
+}
+
+function store_os_distro_information {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  lsb_release --all > "$c_lsb_release_log"
+}
+
+function check_prerequisites {
+  # shellcheck disable=SC2119
+  print_step_info_header
+  if [[ $(id -u) -ne 0 ]]; then
+    echo 'This script must be run with administrative privileges!'
+    exit 1
+  fi
+  if [[ ! -r /root/.ssh/authorized_keys ]]; then
+    echo "SSH pubkey file is absent, please add it to the rescue system setting, then reboot into rescue system and run the script"
+    exit 1
+  fi
+  if ! dpkg-query --showformat="\${Status}" -W dialog 2> /dev/null | grep -q "install ok installed"; then
+    apt install --yes dialog
+  fi
+}
+
+function initial_load_debian_zed_cache {
+  chroot_execute "mkdir /etc/zfs/zfs-list.cache"
+  chroot_execute "touch /etc/zfs/zfs-list.cache/$v_rpool_name"
+  chroot_execute "ln -sf /usr/lib/zfs-linux/zed.d/history_event-zfs-list-cacher.sh /etc/zfs/zed.d/"
+
+  chroot_execute "zed -F &"
+
+  local success=0
+
+  if [[ ! -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] || [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) == 0 )) ]]; then  
+    chroot_execute "zfs set canmount=noauto $v_rpool_name"
+
+    SECONDS=0
+
+    while (( SECONDS++ <= 120 )); do
+      if [[ -e "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" ]] && (( $(find "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name" -type f -printf '%s' 2> /dev/null) > 0 )); then
+        success=1
+        break
+      else
+        sleep 1
+      fi
+    done
+  else
+    success=1
+  fi
+
+  if (( success != 1 )); then
+    echo "Fatal zed daemon error: the ZFS cache hasn't been updated by ZED!"
+    exit 1
+  fi
+
+  chroot_execute "pkill zed"
+
+  sed -Ei "s|/$c_zfs_mount_dir/?|/|g" "$c_zfs_mount_dir/etc/zfs/zfs-list.cache/$v_rpool_name"
+}
+
+function find_suitable_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  udevadm trigger
+
+  # shellcheck disable=SC2012
+  ls -l /dev/disk/by-id | tail -n +2 | perl -lane 'print "@F[8..10]"' > "$c_disks_log"
+
+  local candidate_disk_ids
+  local mounted_devices
+
+  candidate_disk_ids=$(find /dev/disk/by-id -regextype awk -regex '.+/(ata|nvme|scsi)-.+' -not -regex '.+-part[0-9]+$' | sort)
+  mounted_devices="$(df | awk 'BEGIN {getline} {print $1}' | xargs -n 1 lsblk -no pkname 2> /dev/null | sort -u || true)"
+
+  while read -r disk_id || [[ -n "$disk_id" ]]; do
+    local device_info
+
+    device_info="$(udevadm info --query=property "$(readlink -f "$disk_id")")"
+    block_device_basename="$(basename "$(readlink -f "$disk_id")")"
+
+    if ! grep -q '^ID_TYPE=cd$' <<< "$device_info"; then
+      if ! grep -q "^$block_device_basename\$" <<< "$mounted_devices"; then
+        v_suitable_disks+=("$disk_id")
+      fi
+    fi
+
+    cat >> "$c_disks_log" << LOG
+
+## DEVICE: $disk_id ################################
+
+$(udevadm info --query=property "$(readlink -f "$disk_id")")
+
+LOG
+
+  done < <(echo -n "$candidate_disk_ids")
+
+  if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
+    local dialog_message='No suitable disks have been found!
+
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+'
+    dialog --msgbox "$dialog_message" 30 100
+
+    exit 1
+  fi
+
+  print_variables v_suitable_disks
+}
+
+function select_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  while true; do
+    local menu_entries_option=()
+
+    if [[ ${#v_suitable_disks[@]} -eq 1 ]]; then
+      local disk_selection_status=ON
+    else
+      local disk_selection_status=OFF
+    fi
+
+    for disk_id in "${v_suitable_disks[@]}"; do
+      menu_entries_option+=("$disk_id" "($block_device_basename)" "$disk_selection_status")
+    done
+
+    local dialog_message="Select the ZFS devices (multiple selections can be in mirror or strip).
+
+Devices with mounted partitions, cdroms, and removable devices are not displayed!
+"
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+
+    if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
+      break
+    fi
+  done
+
+  print_variables v_selected_disks
+}
+
+function ask_swap_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local swap_size_invalid_message=
+
+  while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+
+    swap_size_invalid_message="Invalid swap size! "
+  done
+
+  print_variables v_swap_size
+}
+
+function ask_free_tail_space {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local tail_space_invalid_message=
+
+  while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+
+    tail_space_invalid_message="Invalid size! "
+  done
+
+  print_variables v_free_tail_space
+}
+
+function ask_zfs_arc_max_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local zfs_arc_max_invalid_message=
+
+  while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+
+    zfs_arc_max_invalid_message="Invalid size! "
+  done
+
+  print_variables v_zfs_arc_max_mb
+}
+
+
+function ask_pool_names {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local bpool_name_invalid_message=
+
+  while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+
+    bpool_name_invalid_message="Invalid pool name! "
+  done
+  local rpool_name_invalid_message=
+
+  while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+
+    rpool_name_invalid_message="Invalid pool name! "
+  done
+
+  print_variables v_bpool_name v_rpool_name
+}
+
+function ask_pool_tweaks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+
+  print_variables v_bpool_tweaks v_rpool_tweaks
+}
+
+
+function ask_root_password {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  set +x
+  local password_invalid_message=
+  local password_repeat=-
+
+  while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+
+    password_invalid_message="Passphrase empty, or not matching! "
+  done
+  set -x
+}
+
+function ask_encryption {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
+    v_encrypt_rpool=1
+  fi
+  set +x
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    local passphrase_invalid_message=
+    local passphrase_repeat=-
+    while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+
+      passphrase_invalid_message="Passphrase too short, or not matching! "
+    done
+  fi
+  set -x
+}
+
+function ask_zfs_experimental {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+    v_zfs_experimental=1
+  fi
+}
+
+function ask_hostname {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local hostname_invalid_message=
+
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+
+    hostname_invalid_message="Invalid host name! "
+  done
+
+  print_variables v_hostname
+}
+
+function determine_kernel_variant {
+  if dmidecode | grep -q vServer; then
+    v_kernel_variant="-cloud"
+  fi
+}
+
+function chroot_execute {
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
+}
+
+function unmount_and_export_fs {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  for virtual_fs_dir in dev sys proc; do
+    umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+  done
+
+  local max_unmount_wait=5
+  echo -n "Waiting for virtual filesystems to unmount "
+
+  SECONDS=0
+
+  for virtual_fs_dir in dev sys proc; do
+    while mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir" && [[ $SECONDS -lt $max_unmount_wait ]]; do
+      sleep 0.5
+      echo -n .
+    done
+  done
+
+  echo
+
+  for virtual_fs_dir in dev sys proc; do
+    if mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir"; then
+      echo "Re-issuing umount for $c_zfs_mount_dir/$virtual_fs_dir"
+      umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+    fi
+  done
+
+  SECONDS=0
+  zpools_exported=99
+  echo "===========exporting zfs pools============="
+  set +e
+  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do    
+    if zpool export -a 2> /dev/null; then
+      zpools_exported=1
+      echo "all zfs pools were succesfully exported"
+      break;
+    else
+      sleep 1
+     fi
+  done
+  set -e
+  if (( zpools_exported != 1 )); then
+    echo "failed to export zfs pools"
+    exit 1
+  fi
+}
+
+#################### MAIN ################################
+export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
+
+check_prerequisites
+
+activate_debug
+
+display_intro_banner
+
+find_suitable_disks
+
+select_disks
+
+ask_swap_size
+
+ask_free_tail_space
+
+ask_pool_names
+
+ask_pool_tweaks
+
+ask_encryption
+
+ask_zfs_arc_max_size
+
+ask_zfs_experimental
+
+ask_root_password
+
+ask_hostname
+
+determine_kernel_variant
+
+clear
+
+echo "===========remove unused kernels in rescue system========="
+for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" | cut -s -d "/" -f 4); do
+  if dpkg -l "linux-headers-$kver" 2>/dev/null | grep -q "^ii"; then
+    apt purge --yes "linux-headers-$kver"
+  fi
+  if dpkg -l "linux-image-$kver" 2>/dev/null | grep -q "^ii"; then
+    apt purge --yes "linux-image-$kver"
+  fi
+done
+
+echo "======= installing zfs on rescue system =========="
+
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
+  apt update
+  export PATH=$PATH:/usr/sbin
+  zfs --version
+
+echo "======= partitioning the disk =========="
+
+  if [[ $v_free_tail_space -eq 0 ]]; then
+    tail_space_parameter=0
+  else
+    tail_space_parameter="-${v_free_tail_space}G"
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    wipefs --all --force "$selected_disk"
+    if (( c_efimode_enabled == 1 )); then
+      sgdisk -a1 -n1:24K:+1G            -t1:EF00 "$selected_disk" # EFI partition
+    else
+      sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
+    fi
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
+  done
+
+  udevadm settle
+
+echo "======= create zfs pools and datasets =========="
+
+  encryption_options=()
+  rpool_disks_partitions=()
+  bpool_disks_partitions=()
+
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    encryption_options=(-O "encryption=aes-256-gcm" -O "keylocation=prompt" -O "keyformat=passphrase")
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    rpool_disks_partitions+=("${selected_disk}-part3")
+    bpool_disks_partitions+=("${selected_disk}-part2")
+  done
+
+  pools_mirror_option=
+  if [[ ${#v_selected_disks[@]} -gt 1 ]]; then
+    if dialog --defaultno --yesno "Do you want to use mirror mode for ${v_selected_disks[*]}?" 30 100; then 
+      pools_mirror_option=mirror
+    fi
+  fi
+
+# shellcheck disable=SC2086
+zpool create \
+  -m none \
+  -o cachefile=/etc/zpool.cache \
+  -o compatibility=grub2 \
+  -O mountpoint=/boot -R $c_zfs_mount_dir -f \
+  $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
+
+# shellcheck disable=SC2086
+echo -n "$v_passphrase" | zpool create \
+  -m none \
+  $v_rpool_tweaks \
+  -o cachefile=/etc/zpool.cache \
+  "${encryption_options[@]}" \
+  -O mountpoint=/ -R $c_zfs_mount_dir -f \
+  $v_rpool_name $pools_mirror_option "${rpool_disks_partitions[@]}"
+
+zfs create -o canmount=off -o mountpoint=none "$v_rpool_name/ROOT"
+zfs create -o canmount=off -o mountpoint=none "$v_bpool_name/BOOT"
+
+zfs create -o canmount=noauto -o mountpoint=/ "$v_rpool_name/ROOT/debian"
+zfs mount "$v_rpool_name/ROOT/debian"
+
+zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/debian"
+zfs mount "$v_bpool_name/BOOT/debian"
+
+zfs create                                 "$v_rpool_name/home"
+#zfs create -o mountpoint=/root             "$v_rpool_name/home/root"
+zfs create -o canmount=off                 "$v_rpool_name/var"
+zfs create                                 "$v_rpool_name/var/log"
+zfs create                                 "$v_rpool_name/var/spool"
+
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/cache"
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/tmp"
+chmod 1777 "$c_zfs_mount_dir/var/tmp"
+
+zfs create                                 "$v_rpool_name/srv"
+
+zfs create -o canmount=off                 "$v_rpool_name/usr"
+zfs create                                 "$v_rpool_name/usr/local"
+
+zfs create                                 "$v_rpool_name/var/mail"
+
+zfs create -o com.sun:auto-snapshot=false -o canmount=on -o mountpoint=/tmp "$v_rpool_name/tmp"
+chmod 1777 "$c_zfs_mount_dir/tmp"
+
+if [[ $v_swap_size -gt 0 ]]; then
+  zfs create \
+    -V "${v_swap_size}G" -b "$(getconf PAGESIZE)" \
+    -o compression=zle -o logbias=throughput -o sync=always -o primarycache=metadata -o secondarycache=none -o com.sun:auto-snapshot=false \
+    "$v_rpool_name/swap"
+
+  udevadm settle
+
+  mkswap -f "/dev/zvol/$v_rpool_name/swap"
+fi
+
+if (( c_efimode_enabled == 1 )); then
+echo "======= create filesystem on EFI partition(s) =========="
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    mkfs.fat -F32 "${selected_disk}-part1"
+  done
+  mkdir -p "$c_zfs_mount_dir/boot/efi"
+  mount "${v_selected_disks[0]}-part1" "$c_zfs_mount_dir/boot/efi"
+fi
+
+echo "======= setting up initial system packages =========="
+debootstrap --arch=amd64 bookworm "$c_zfs_mount_dir" "$c_deb_packages_repo"
+
+zfs set devices=off "$v_rpool_name"
+
+echo "======= setting up the network =========="
+
+echo "$v_hostname" > $c_zfs_mount_dir/etc/hostname
+
+cat > "$c_zfs_mount_dir/etc/hosts" <<CONF
+127.0.1.1 ${v_hostname}
+127.0.0.1 localhost
+
+# The following lines are desirable for IPv6 capable hosts
+::1 ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+CONF
+
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
+
+cat <<CONF > "$c_zfs_mount_dir/etc/systemd/network/10-eth0.network"
+[Match]
+Name=eth0
+
+[Network]
+DHCP=ipv4
+Address=${ip6addr_prefix}:1/64
+Gateway=fe80::1
+CONF
+chroot_execute "systemctl enable systemd-networkd.service"
+
+echo "======= preparing the jail for chroot =========="
+for virtual_fs_dir in proc sys dev; do
+  mount --rbind "/$virtual_fs_dir" "$c_zfs_mount_dir/$virtual_fs_dir"
+done
+
+echo "======= setting apt repos =========="
+cat > "$c_zfs_mount_dir/etc/apt/sources.list" <<CONF
+deb $c_deb_packages_repo bookworm main contrib non-free non-free-firmware
+deb $c_deb_packages_repo bookworm-updates main contrib non-free non-free-firmware
+deb $c_deb_security_repo bookworm-security main contrib non-free non-free-firmware
+deb $c_deb_packages_repo bookworm-backports main contrib non-free non-free-firmware
+CONF
+
+chroot_execute "apt update"
+
+echo "======= setting locale, console and language =========="
+chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils"
+sed -i 's/# en_US.UTF-8/en_US.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_AT.UTF-8/de_AT.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_DE.UTF-8/de_DE.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+
+chroot_execute 'cat <<CONF | debconf-set-selections
+locales locales/default_environment_locale      select  en_US.UTF-8
+keyboard-configuration  keyboard-configuration/store_defaults_in_debconf_db     boolean true
+keyboard-configuration  keyboard-configuration/variant  select  German
+keyboard-configuration  keyboard-configuration/unsupported_layout       boolean true
+keyboard-configuration  keyboard-configuration/modelcode        string  pc105
+keyboard-configuration  keyboard-configuration/unsupported_config_layout        boolean true
+keyboard-configuration  keyboard-configuration/layout   select  German
+keyboard-configuration  keyboard-configuration/layoutcode       string  de
+keyboard-configuration  keyboard-configuration/optionscode      string
+keyboard-configuration  keyboard-configuration/toggle   select  No toggling
+keyboard-configuration  keyboard-configuration/xkb-keymap       select  de
+keyboard-configuration  keyboard-configuration/switch   select  No temporary switch
+keyboard-configuration  keyboard-configuration/unsupported_config_options       boolean true
+keyboard-configuration  keyboard-configuration/ctrl_alt_bksp    boolean false
+keyboard-configuration  keyboard-configuration/variantcode      string
+keyboard-configuration  keyboard-configuration/model    select  Generic 105-key PC (intl.)
+keyboard-configuration  keyboard-configuration/altgr    select  The default for the keyboard layout
+keyboard-configuration  keyboard-configuration/compose  select  No compose key
+keyboard-configuration  keyboard-configuration/unsupported_options      boolean true
+console-setup   console-setup/fontsize-fb47     select  8x16
+console-setup   console-setup/store_defaults_in_debconf_db      boolean true
+console-setup   console-setup/codeset47 select  # Latin1 and Latin5 - western Europe and Turkic languages
+console-setup   console-setup/fontface47        select  Fixed
+console-setup   console-setup/fontsize  string  8x16
+console-setup   console-setup/charmap47 select  UTF-8
+console-setup   console-setup/fontsize-text47   select  8x16
+console-setup   console-setup/codesetcode       string  Lat15
+tzdata tzdata/Areas select Europe
+tzdata tzdata/Zones/Europe select Vienna
+CONF'
+
+chroot_execute "dpkg-reconfigure locales -f noninteractive"
+echo -e "LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8\n" >> "$c_zfs_mount_dir/etc/environment"
+chroot_execute "apt install -qq --yes keyboard-configuration console-setup"
+chroot_execute "dpkg-reconfigure keyboard-configuration -f noninteractive"
+chroot_execute "dpkg-reconfigure console-setup -f noninteractive"
+chroot_execute "setupcon"
+
+chroot_execute "rm -f /etc/localtime /etc/timezone"
+chroot_execute "dpkg-reconfigure tzdata -f noninteractive"
+
+echo "======= installing latest kernel============="
+# linux-headers-generic linux-image-generic
+chroot_execute "apt install --yes linux-image${v_kernel_variant}-amd64 linux-headers${v_kernel_variant}-amd64 dpkg-dev"
+
+echo "======= installing aux packages =========="
+chroot_execute "apt install --yes man wget curl software-properties-common nano htop gnupg"
+
+echo "======= installing zfs packages =========="
+chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
+
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
+  chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
+else
+  chroot_execute "apt install -t bookworm-backports --yes zfs-initramfs zfs-dkms zfsutils-linux"
+fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
+echo "======= installing OpenSSH and network tooling =========="
+chroot_execute "apt install --yes openssh-server net-tools"
+
+echo "======= setup OpenSSH  =========="
+sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+chroot_execute "rm /etc/ssh/ssh_host_*"
+chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
+
+echo "======= set root password =========="
+chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
+
+echo "======= setting up zfs cache =========="
+
+cp /etc/zpool.cache "$c_zfs_mount_dir/etc/zfs/zpool.cache"
+
+echo "========setting up zfs module parameters========"
+chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
+
+echo "======= setting up grub =========="
+if (( c_efimode_enabled == 1 )); then
+  chroot_execute "apt install --yes grub-efi-amd64"
+else
+  chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
+  chroot_execute "apt install --yes grub-legacy"
+  chroot_execute "apt install --yes grub-pc"
+fi
+
+if (( c_efimode_enabled == 1 )); then
+  #chroot_execute grub-probe /boot
+  chroot_execute grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=debian --recheck
+else
+  for disk in ${v_selected_disks[@]}; do
+    chroot_execute "grub-install --recheck $disk"
+  done
+fi
+
+chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/debian\"|g' /etc/default/grub"
+
+chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
+chroot_execute "sed -i 's/splash//g' /etc/default/grub"
+chroot_execute "echo 'GRUB_DISABLE_OS_PROBER=true'   >> /etc/default/grub"
+
+for ((i = 1; i < ${#v_selected_disks[@]}; i++)); do
+  dd if="${v_selected_disks[0]}-part1" of="${v_selected_disks[i]}-part1"
+done
+
+if [[ $v_encrypt_rpool == "1" ]]; then
+  echo "=========set up dropbear=============="
+
+  chroot_execute "apt install --yes dropbear-initramfs"
+  
+  mkdir -p "$c_zfs_mount_dir/etc/dropbear/initramfs"
+  cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/etc/dropbear/initramfs/authorized_keys"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_rsa_key_temp /etc/dropbear/initramfs/dropbear_rsa_host_key"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_ecdsa_key_temp /etc/dropbear/initramfs/dropbear_ecdsa_host_key"
+  chroot_execute "rm -rf /etc/ssh/ssh_host_ecdsa_key_temp"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+
+  rm -rf "$c_zfs_mount_dir/etc/dropbear/initramfs/dropbear_dss_host_key"
+fi
+
+echo "============setup root prompt============"
+cat > "$c_zfs_mount_dir/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+
+echo "========= add root pubkey for login via SSH"
+mkdir -p "$c_zfs_mount_dir/root/.ssh/"
+cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/root/.ssh/authorized_keys"
+
+echo "========running packages upgrade and autoremove==========="
+chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
+
+echo "===========add static route to initramfs via hook to add default routes for Hetzner due to Debian/Ubuntu initramfs DHCP bug ========="
+mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
+cat > "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route" <<'CONF'
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+    echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+
+. /scripts/functions
+# Begin real processing below this line
+
+configure_networking
+
+ip route add 172.31.1.1/255.255.255.255 dev eth0
+ip route add default via 172.31.1.1 dev eth0
+CONF
+
+chmod 755 "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route"
+
+chmod 755 "$c_zfs_mount_dir/etc/network/interfaces"
+
+echo "======= update initramfs =========="
+chroot_execute "update-initramfs -u -k all"
+
+chroot_execute "apt remove cryptsetup* --yes"
+
+echo "======= update grub =========="
+chroot_execute "update-grub"
+
+echo "======= setting up zed =========="
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "zfs set canmount=noauto $v_rpool_name"
+else
+  initial_load_debian_zed_cache
+fi
+
+echo "======= setting mountpoints =========="
+if (( c_efimode_enabled == 1 )); then
+  umount "$c_zfs_mount_dir/boot/efi"
+fi
+
+chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/debian"
+chroot_execute "echo $v_bpool_name/BOOT/debian /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
+
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
+chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/spool"
+chroot_execute "echo $v_rpool_name/var/spool /var/spool zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/tmp"
+chroot_execute "echo $v_rpool_name/var/tmp /var/tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
+chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+
+echo "========= add swap, if defined"
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
+
+chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
+
+echo "======= unmounting filesystems and zfs pools =========="
+unmount_and_export_fs
+
+echo "======== setup complete, rebooting ==============="
+reboot

hetzner-debian13-zfs-setup.sh

@@ -0,0 +1,951 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Debian 13 with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname and ZFS ARC cache size
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -euo pipefail
+
+# ---- Configuration ----
+SYSTEM_HOSTNAME=""
+ROOT_PASSWORD=""
+ZFS_POOL=""
+DEBIAN_CODENAME="trixie"   # Debian 13
+TARGET="/mnt/debian"
+
+ZBM_BIOS_URL="https://github.com/zbm-dev/zfsbootmenu/releases/download/v3.0.1/zfsbootmenu-release-x86_64-v3.0.1-linux6.1.tar.gz"
+ZBM_EFI_URL="https://github.com/zbm-dev/zfsbootmenu/releases/download/v3.0.1/zfsbootmenu-release-x86_64-v3.0.1-linux6.1.EFI"
+
+MAIN_BOOT="/main_boot"
+
+# Hetzner mirrors for Debian
+MIRROR_SITE="https://mirror.hetzner.com"
+MIRROR_MAIN="deb ${MIRROR_SITE}/debian/packages ${DEBIAN_CODENAME} main contrib non-free non-free-firmware"
+MIRROR_UPDATES="deb ${MIRROR_SITE}/debian/packages ${DEBIAN_CODENAME}-updates main contrib non-free non-free-firmware"
+MIRROR_SECURITY="deb ${MIRROR_SITE}/debian/security ${DEBIAN_CODENAME}-security main contrib non-free non-free-firmware"
+
+# Global variables
+INSTALL_DISK=""
+EFI_MODE=false
+BOOT_LABEL=""
+BOOT_TYPE=""
+BOOT_PART=""
+ZFS_PART=""
+
+# ---- User Input Functions ----
+function setup_whiptail_colors {
+    # Green text on black background - classic terminal theme
+    export NEWT_COLORS='
+    root=green,black
+    window=green,black
+    shadow=green,black
+    border=green,black
+    title=green,black
+    textbox=green,black
+    button=black,green
+    listbox=green,black
+    actlistbox=black,green
+    actsellistbox=black,green
+    checkbox=green,black
+    actcheckbox=black,green
+    entry=green,black
+    label=green,black
+    '
+}
+
+function check_whiptail {
+    if ! command -v whiptail &> /dev/null; then
+        echo "Installing whiptail..."
+        apt update
+        apt install -y whiptail
+    fi
+    setup_whiptail_colors
+}
+
+function get_hostname {
+    while true; do
+        SYSTEM_HOSTNAME=$(whiptail \
+            --title " System Hostname " \
+            --inputbox "\nEnter the hostname for the new system:" \
+            10 60 "zfs-debian" \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            echo "Installation cancelled by user."
+            exit 1
+        fi
+        
+        # Validate hostname
+        if [[ "$SYSTEM_HOSTNAME" =~ ^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$ ]] && [[ ${#SYSTEM_HOSTNAME} -le 63 ]]; then
+            break
+        else
+            whiptail \
+                --title " Invalid Hostname " \
+                --msgbox "Invalid hostname. Please use only letters, numbers, and hyphens. Must start and end with alphanumeric character. Maximum 63 characters." \
+                12 60
+        fi
+    done
+}
+
+function get_zfs_pool_name {
+    while true; do
+        ZFS_POOL=$(whiptail \
+            --title " ZFS Pool Name " \
+            --inputbox "\nEnter the name for the ZFS pool:" \
+            10 60 "rpool" \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            echo "Installation cancelled by user."
+            exit 1
+        fi
+        
+        # Validate ZFS pool name
+        if [[ "$ZFS_POOL" =~ ^[a-zA-Z][a-zA-Z0-9_-]*$ ]] && [[ ${#ZFS_POOL} -le 255 ]]; then
+            break
+        else
+            whiptail \
+                --title " Invalid Pool Name " \
+                --msgbox "Invalid ZFS pool name. Must start with a letter and contain only letters, numbers, hyphens, and underscores. Maximum 255 characters." \
+                12 60
+        fi
+    done
+}
+
+function get_root_password {
+    while true; do
+        # Get first password input
+        local password1
+        local password2
+        
+        password1=$(whiptail \
+            --title " Root Password " \
+            --passwordbox "\nEnter root password (input hidden):" \
+            10 60 \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            echo "Installation cancelled by user."
+            exit 1
+        fi
+        
+        # Get password confirmation
+        password2=$(whiptail \
+            --title " Confirm Root Password " \
+            --passwordbox "\nConfirm root password (input hidden):" \
+            10 60 \
+            3>&1 1>&2 2>&3)
+        
+        exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            echo "Installation cancelled by user."
+            exit 1
+        fi
+        
+        # Check if passwords match
+        if [ "$password1" = "$password2" ]; then
+            if [ -n "$password1" ]; then
+                ROOT_PASSWORD="$password1"
+                break
+            else
+                whiptail \
+                    --title " Empty Password " \
+                    --msgbox "Password cannot be empty. Please enter a password." \
+                    10 50
+            fi
+        else
+            whiptail \
+                --title " Password Mismatch " \
+                --msgbox "Passwords do not match. Please try again." \
+                10 50
+        fi
+    done
+}
+
+function show_summary_and_confirm {
+    local summary="Please review the installation settings:
+
+Hostname: $SYSTEM_HOSTNAME
+ZFS Pool: $ZFS_POOL
+Debian Version: $DEBIAN_CODENAME (13)
+Target: $TARGET
+Boot Mode: $([ "$EFI_MODE" = true ] && echo "EFI" || echo "BIOS")
+Install Disk: $INSTALL_DISK
+
+*** WARNING: This will DESTROY ALL DATA on $INSTALL_DISK! ***
+
+Do you want to continue with the installation?"
+    
+    if whiptail \
+        --title " Installation Summary " \
+        --yesno "$summary" \
+        18 60; then
+        # User confirmed - just continue silently
+        echo "User confirmed installation. Starting now..."
+    else
+        echo "Installation cancelled by user."
+        exit 1
+    fi
+}
+
+function get_user_input {
+    echo "======= Gathering Installation Parameters =========="
+    check_whiptail
+    
+    # Show welcome message
+    whiptail \
+        --title " ZFS Debian Installer " \
+        --msgbox "Welcome to the ZFS Debian Installer for Hetzner Cloud.\n\nThis script will install Debian 13 with ZFS root on your server." \
+        12 60
+    
+    # Get user inputs
+    get_hostname
+    get_zfs_pool_name
+    get_root_password
+}
+
+# ---- System Detection Functions ----
+function detect_efi {
+    echo "======= Detecting EFI support =========="
+    
+    if [ -d /sys/firmware/efi ]; then
+        echo "✓ EFI firmware detected"
+        EFI_MODE=true
+        BOOT_LABEL="EFI"
+        BOOT_TYPE="ef00"
+    else
+        echo "✓ Legacy BIOS mode detected"
+        EFI_MODE=false
+        BOOT_LABEL="boot"
+        BOOT_TYPE="8300"
+    fi
+}
+
+function find_install_disk {
+    echo "======= Finding install disk =========="
+    
+    local candidate_disks=()
+    
+    # Use lsblk to find all unmounted, writable disks
+    while IFS= read -r disk; do
+        [[ -n "$disk" ]] && candidate_disks+=("$disk")
+    done < <(lsblk -npo NAME,TYPE,RO,MOUNTPOINT | awk '
+        $2 == "disk" && $3 == "0" && $4 == "" {print $1}
+    ')
+    
+    if [[ ${#candidate_disks[@]} -eq 0 ]]; then
+        echo "No suitable installation disks found" >&2
+        echo "Looking for: unmounted, writable disks without partitions in use" >&2
+        exit 1
+    fi
+    
+    INSTALL_DISK="${candidate_disks[0]}"
+    echo "Using installation disk: $INSTALL_DISK"
+    
+    # Show all available disks for verification
+    echo "All available disks:"
+    lsblk -o NAME,SIZE,TYPE,MOUNTPOINT,RO | grep -v loop
+}
+
+# ---- Rescue System Preparation Functions ----
+function remove_unused_kernels {
+    echo "=========== Removing unused kernels in rescue system =========="
+    for kver in $(find /lib/modules/* -maxdepth 0 -type d \
+                    | grep -v "$(uname -r)" \
+                    | cut -s -d "/" -f 4); do
+
+        for pkg in "linux-headers-$kver" "linux-image-$kver"; do
+            if dpkg -l "$pkg" 2>/dev/null | grep -q '^ii'; then
+                echo "Purging $pkg ..."
+                apt purge --yes "$pkg"
+            else
+                echo "Package $pkg not installed, skipping."
+            fi
+        done
+    done
+}
+
+function install_zfs_on_rescue_system {
+    echo "======= Installing ZFS on rescue system =========="
+    echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
+    # Enable backports for newer ZFS version
+    echo "deb http://mirror.hetzner.com/debian/packages bookworm-backports main contrib" > /etc/apt/sources.list.d/backports.list
+    apt update
+    apt -t bookworm-backports install -y zfsutils-linux
+}
+
+# ---- Disk Partitioning Functions ----
+function partition_disk {
+    echo "======= Partitioning disk =========="
+    sgdisk -Z "$INSTALL_DISK"  
+    
+    if [ "$EFI_MODE" = true ]; then
+        echo "Creating EFI partition layout"
+        # EFI System Partition (ESP) - 64MB is plenty for ZFSBootMenu
+        sgdisk -n1:1M:+128M -t1:ef00 -c1:"EFI" "$INSTALL_DISK"
+        # ZFS partition
+        sgdisk -n2:0:0   -t2:bf00 -c2:"zfs"  "$INSTALL_DISK"
+    else
+        echo "Creating BIOS partition layout"
+        # /boot partition - 64MB is also sufficient for BIOS ZFSBootMenu
+        sgdisk -n1:1M:+128M -t1:8300 -c1:"boot" "$INSTALL_DISK"
+        # ZFS partition
+        sgdisk -n2:0:0   -t2:bf00 -c2:"zfs"  "$INSTALL_DISK"
+        # Set legacy BIOS bootable flag
+        sgdisk -A 1:set:2 "$INSTALL_DISK"
+    fi
+    
+    partprobe "$INSTALL_DISK" || true
+    udevadm settle
+    
+    # Set partition variables based on mode
+    if [ "$EFI_MODE" = true ]; then
+        BOOT_PART="$(blkid -t PARTLABEL='EFI' -o device)"
+        ZFS_PART="$(blkid -t PARTLABEL='zfs' -o device)"
+        # Format ESP as FAT32
+        mkfs.fat -F 32 -n EFI "$BOOT_PART"
+    else
+        BOOT_PART="$(blkid -t PARTLABEL='boot' -o device)"
+        ZFS_PART="$(blkid -t PARTLABEL='zfs' -o device)"
+        mkfs.ext4 -F -L boot "$BOOT_PART"
+    fi
+}
+
+# ---- ZFS Pool and Dataset Functions ----
+function create_zfs_pool {
+    echo "======= Creating ZFS pool =========="
+    # Clean up any existing ZFS binaries in PATH
+    rm -f "$(which zfs)" 2>/dev/null || true
+    rm -f "$(which zpool)" 2>/dev/null || true
+    
+    export PATH=/usr/sbin:$PATH
+    modprobe zfs
+    
+    zpool create -f -o ashift=12 \
+    -o cachefile="/etc/zfs/zpool.cache" \
+    -O compression=lz4 \
+    -O acltype=posixacl \
+    -O xattr=sa \
+    -O mountpoint=none \
+    "$ZFS_POOL" "$ZFS_PART"
+
+    zfs create -o mountpoint=none   "$ZFS_POOL/ROOT"
+    zfs create -o mountpoint=legacy "$ZFS_POOL/ROOT/debian"
+
+    echo "======= Assigning $ZFS_POOL/ROOT/debian dataset as bootable =========="
+    zpool set bootfs="$ZFS_POOL/ROOT/debian" "$ZFS_POOL"
+    zpool set cachefile="/etc/zfs/zpool.cache" "$ZFS_POOL"
+}
+
+function create_additional_zfs_datasets {
+    echo "======= Creating additional ZFS datasets with TEMPORARY mountpoints =========="
+    
+    # Ensure parent datasets are created first
+    zfs create -o mountpoint=none "$ZFS_POOL/ROOT/debian/var"
+    zfs create -o mountpoint=none "$ZFS_POOL/ROOT/debian/var/cache"
+    
+    # Create leaf datasets with temporary mountpoints under $TARGET
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/tmp" "$ZFS_POOL/ROOT/debian/tmp"
+    zfs set devices=off "$ZFS_POOL/ROOT/debian/tmp"
+    
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/var/tmp" "$ZFS_POOL/ROOT/debian/var/tmp"
+    zfs set devices=off "$ZFS_POOL/ROOT/debian/var/tmp"
+    
+    zfs create -o mountpoint="$TARGET/var/log" "$ZFS_POOL/ROOT/debian/var/log"    
+    zfs set atime=off "$ZFS_POOL/ROOT/debian/var/log"
+    
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/var/cache/apt" "$ZFS_POOL/ROOT/debian/var/cache/apt"    
+    zfs set atime=off "$ZFS_POOL/ROOT/debian/var/cache/apt"
+    
+    # Create home dataset separately
+    zfs create -o mountpoint="$TARGET/home" "$ZFS_POOL/home"
+    
+    # Mount all datasets
+    zfs mount -a
+    
+    # Set permissions on the actual ZFS datasets
+    echo "Setting permissions on ZFS datasets..."
+    chmod 1777 "$TARGET/tmp"
+    chmod 1777 "$TARGET/var/tmp"
+    echo "✓ Temp directory permissions set (1777)"
+}
+
+function set_final_mountpoints {
+    echo "======= Setting final mountpoints =========="
+    
+    # Leaf datasets - actual system mountpoints
+    zfs set mountpoint=/tmp "$ZFS_POOL/ROOT/debian/tmp"
+    zfs set mountpoint=/var/tmp "$ZFS_POOL/ROOT/debian/var/tmp"
+    zfs set mountpoint=/var/log "$ZFS_POOL/ROOT/debian/var/log"
+    zfs set mountpoint=/var/cache/apt "$ZFS_POOL/ROOT/debian/var/cache/apt"
+    
+    # Home dataset - separate from OS
+    zfs set mountpoint=/home "$ZFS_POOL/home"    
+    echo ""
+    echo "Detailed dataset listing:"
+    zfs list -o name,mountpoint -r "$ZFS_POOL"
+}
+
+# ---- System Bootstrap Functions ----
+function bootstrap_debian_system {
+    echo "======= Bootstrapping Debian to temporary directory =========="
+    
+    # Install debootstrap if not available
+    if ! command -v debootstrap &> /dev/null; then
+        echo "Installing debootstrap..."
+        apt update
+        apt install -y debootstrap
+    fi
+
+    #echo "======= Copying staged system to ZFS datasets =========="
+    # Mount root dataset for copying
+    mkdir -p "$TARGET"
+    mount -t zfs "$ZFS_POOL/ROOT/debian" "$TARGET"
+
+    create_additional_zfs_datasets
+
+    # Bootstrap Debian 13 (Trixie) - include dbus to satisfy systemd-resolved dependency
+    debootstrap \
+        --components=main,contrib,non-free,non-free-firmware \
+        --include=initramfs-tools,dbus,locales,debconf-i18n,apt-utils,keyboard-configuration,console-setup,kbd,zstd,systemd-resolved,systemd-timesyncd \
+        "$DEBIAN_CODENAME" \
+        "$TARGET" \
+        "$MIRROR_SITE/debian/packages"    
+
+}
+
+function setup_chroot_environment {
+    echo "======= Mounting virtual filesystems for chroot =========="
+    mount -t proc proc "$TARGET/proc"
+    mount -t sysfs sysfs "$TARGET/sys"
+    
+    # Only mount specific tmpfs directories, not the entire /run
+    mkdir -p "$TARGET/run/lock" "$TARGET/run/shm"
+    mount -t tmpfs tmpfs "$TARGET/run/lock"
+    mount -t tmpfs tmpfs "$TARGET/run/shm"
+    mount -t tmpfs tmpfs "$TARGET/tmp"
+    
+    mount --bind /dev "$TARGET/dev"
+    mount --bind /dev/pts "$TARGET/dev/pts"
+}
+
+# ---- System Configuration Functions ----
+function configure_basic_system {
+    echo "======= Configuring basic system settings =========="
+    chroot "$TARGET" /bin/bash <<EOF
+set -euo pipefail
+
+# Set hostname from variable
+echo "$SYSTEM_HOSTNAME" > /etc/hostname
+
+# Configure timezone (Vienna)
+echo "Europe/Vienna" > /etc/timezone
+ln -sf /usr/share/zoneinfo/Europe/Vienna /etc/localtime
+
+# Generate locales
+cat > /etc/locale.gen <<'LOCALES'
+en_US.UTF-8 UTF-8
+de_AT.UTF-8 UTF-8
+fr_FR.UTF-8 UTF-8  
+ru_RU.UTF-8 UTF-8
+LOCALES
+
+locale-gen
+
+# Set default locale
+update-locale LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
+
+# Configure keyboard for German and US with Alt+Shift toggle
+cat > /etc/default/keyboard <<'KEYBOARD'
+# KEYBOARD CONFIGURATION FILE
+
+# Consult the keyboard(5) manual page.
+
+XKBMODEL="pc105"
+XKBLAYOUT="de,ru"
+XKBVARIANT=","
+XKBOPTIONS="grp:ctrl_shift_toggle"
+
+BACKSPACE="guess"
+KEYBOARD
+
+# Apply keyboard configuration to console
+setupcon --force
+
+# Update /etc/hosts with the hostname
+echo "127.0.0.1 localhost" > /etc/hosts
+echo "127.0.1.1 $SYSTEM_HOSTNAME" >> /etc/hosts
+echo "::1 localhost ip6-localhost ip6-loopback" >> /etc/hosts
+echo "ff02::1 ip6-allnodes" >> /etc/hosts
+echo "ff02::2 ip6-allrouters" >> /etc/hosts
+
+# Set proper permissions for ZFS datasets
+chmod 1777 /tmp
+chmod 1777 /var/tmp
+EOF
+
+    echo "======= Configuration Summary ======="
+    chroot "$TARGET" /bin/bash <<'EOF'
+echo "Hostname: $(cat /etc/hostname)"
+echo "Timezone: $(cat /etc/timezone)"
+echo "Current time: $(date)"
+echo "Default locale: $(grep LANG /etc/default/locale)"
+echo "Available locales:"
+locale -a | grep -E "(en_US|de_AT|fr_FR|ru_RU)"
+echo "Keyboard layout: $(grep XKBLAYOUT /etc/default/keyboard)"
+EOF
+}
+
+function install_system_packages {
+    echo "======= Installing ZFS and essential packages in chroot =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+
+# Configure sources.list for Debian 13
+cat > /etc/apt/sources.list <<'SOURCES'
+deb https://mirror.hetzner.com/debian/packages trixie main contrib non-free non-free-firmware
+deb https://mirror.hetzner.com/debian/packages trixie-updates main contrib non-free non-free-firmware
+deb https://mirror.hetzner.com/debian/security trixie-security main contrib non-free non-free-firmware
+deb https://mirror.hetzner.com/debian/packages trixie-backports main contrib non-free non-free-firmware
+SOURCES
+
+# Update package lists
+apt update
+
+# Install kernel
+apt install -y --no-install-recommends linux-image-cloud-amd64 linux-headers-cloud-amd64
+
+# Install essential packages
+apt install -y curl nano htop net-tools ssh \
+    apt-transport-https ca-certificates gnupg dirmngr \
+    firmware-linux-free apparmor
+
+echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
+
+apt install -y -t trixie-backports zfsutils-linux zfs-initramfs zfs-dkms
+
+# Get the actual kernel version installed in the chroot
+KERNEL_VERSION=$(ls /lib/modules/ | head -n1)
+echo "Detected kernel version: $KERNEL_VERSION"
+
+# Verify ZFS module is available in the chroot filesystem
+echo "=== Verifying ZFS module in chroot ==="
+if find "/lib/modules/$KERNEL_VERSION" -name "*zfs*" -type f | grep -q .; then
+    echo "✓ ZFS module files found in /lib/modules/$KERNEL_VERSION/"
+    find "/lib/modules/$KERNEL_VERSION" -name "*zfs*" -type f
+else
+    echo "✗ ZFS module files not found - attempting DKMS rebuild"
+    dkms autoinstall -k "$KERNEL_VERSION" || true
+    depmod -a "$KERNEL_VERSION"
+    
+    # Check again after DKMS rebuild
+    if find "/lib/modules/$KERNEL_VERSION" -name "*zfs*" -type f | grep -q .; then
+        echo "✓ ZFS module files found after DKMS rebuild"
+    else
+        echo "✗ ZFS module files still not found - this may cause boot issues"
+    fi
+fi
+
+# Ensure ZFS module is included in initramfs
+echo "zfs" >> /etc/initramfs-tools/modules
+
+# Generate initramfs with ZFS support
+update-initramfs -u -k all
+
+# Verify kernel installation
+echo "Installed kernel packages:"
+dpkg -l | grep linux-image
+echo "Kernel version:"
+ls /lib/modules/
+echo "Kernel files in ZFS dataset:"
+ls -la /boot/vmlinuz* /boot/initrd.img* 2>/dev/null || echo "No kernel files found"
+EOF
+}
+
+function verify_initramfs {
+    echo "======= Verifying initramfs contents =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+
+echo "=== Checking initramfs for ZFS components ==="
+for initrd in /boot/initrd.img-*; do
+    if [ -f "$initrd" ]; then
+        echo "Checking: $initrd"
+        lsinitramfs "$initrd" | grep -E "(zfs|pool|dataset|spl)" | head -10 || echo "No ZFS components found (this might be normal for first check)"
+        echo "---"
+    fi
+done
+
+echo "=== Checking ZFS module files on disk ==="
+KERNEL_VERSION=$(ls /lib/modules/ | head -n1)
+find "/lib/modules/$KERNEL_VERSION" -name "*zfs*" -type f
+
+echo "=== Testing ZFS commands ==="
+which zpool && zpool --version || echo "zpool not found"
+which zfs && zfs --version || echo "zfs not found"
+
+echo "=== Checking DKMS status ==="
+dkms status || echo "DKMS not available"
+
+echo "=== Checking if ZFS tools are properly installed ==="
+dpkg -l | grep -E "(zfs|spl)"
+
+EOF
+}
+
+function configure_ssh {
+    echo "======= Setting up OpenSSH =========="
+    mkdir -p "$TARGET/root/.ssh/"
+    cp /root/.ssh/authorized_keys "$TARGET/root/.ssh/authorized_keys"
+    sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$TARGET/etc/ssh/sshd_config"
+    sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$TARGET/etc/ssh/sshd_config"
+
+    chroot "$TARGET" /bin/bash <<'EOF'
+rm /etc/ssh/ssh_host_*
+dpkg-reconfigure openssh-server -f noninteractive
+EOF
+}
+
+function set_root_credentials {
+    echo "======= Setting root password =========="
+    chroot "$TARGET" /bin/bash -c "echo root:$(printf "%q" "$ROOT_PASSWORD") | chpasswd"
+
+    echo "============ Setting up root prompt ============"
+    cat > "$TARGET/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+}
+
+# ---- Bootloader Functions ----
+function setup_efi_boot {
+    echo "======= Setting up EFI boot =========="
+    
+    # Mount EFI System Partition
+    mkdir -p "$MAIN_BOOT"
+    mount "$BOOT_PART" "$MAIN_BOOT"
+    
+    # Create EFI directory structure    
+    mkdir -p "$MAIN_BOOT/EFI/Boot"
+    
+    # Download ZFSBootMenu EFI binary
+    echo "Downloading ZFSBootMenu EFI binary from: $ZBM_EFI_URL"
+    curl -L "$ZBM_EFI_URL" -o "$MAIN_BOOT/EFI/Boot/bootx64.efi"    
+}
+
+function setup_bios_boot {
+    echo "======= Setting up BIOS boot =========="
+    
+    # Mount boot partition
+    mkdir -p "$MAIN_BOOT"
+    mount "$BOOT_PART" "$MAIN_BOOT"
+    
+    # Install extlinux in rescue system if needed
+    if ! command -v extlinux &> /dev/null; then
+        echo "Installing extlinux in rescue system..."
+        apt update
+        apt install -y extlinux
+    fi
+    
+    # Install extlinux
+    extlinux --install "$MAIN_BOOT"
+    
+    # Create extlinux configuration
+    cat > "$MAIN_BOOT/extlinux.conf" << 'EOF'
+DEFAULT zfsbootmenu
+PROMPT 0
+TIMEOUT 0
+
+LABEL zfsbootmenu
+    LINUX /zfsbootmenu/vmlinuz-bootmenu
+    INITRD /zfsbootmenu/initramfs-bootmenu.img
+    APPEND ro quiet
+EOF
+
+    echo "Generated extlinux.conf:"
+    cat "$MAIN_BOOT/extlinux.conf"
+    
+    # Download and install ZFSBootMenu for BIOS
+    local TEMP_ZBM=$(mktemp -d)
+    echo "Downloading ZFSBootMenu for BIOS from: $ZBM_BIOS_URL"
+    curl -L "$ZBM_BIOS_URL" -o "$TEMP_ZBM/zbm.tar.gz"
+    tar -xz -C "$TEMP_ZBM" -f "$TEMP_ZBM/zbm.tar.gz" --strip-components=1
+    
+    # Copy ZFSBootMenu to boot partition
+    mkdir -p "$MAIN_BOOT/zfsbootmenu"
+    cp "$TEMP_ZBM"/vmlinuz* "$MAIN_BOOT/zfsbootmenu/"
+    cp "$TEMP_ZBM"/initramfs* "$MAIN_BOOT/zfsbootmenu/"
+    
+    # Clean up
+    rm -rf "$TEMP_ZBM"
+    
+    echo "ZFSBootMenu files copied to boot partition:"
+    ls -la "$MAIN_BOOT/zfsbootmenu/"
+    
+    # Install MBR and set boot flag
+    dd bs=440 conv=notrunc count=1 if="/usr/lib/EXTLINUX/gptmbr.bin" of="$INSTALL_DISK"
+    parted "$INSTALL_DISK" set 1 boot on
+    
+    echo "BIOS boot setup complete"
+}
+
+function configure_bootloader {
+    echo "======= Setting up boot based on firmware type =========="
+    if [ "$EFI_MODE" = true ]; then
+        setup_efi_boot
+    else
+        setup_bios_boot
+    fi
+
+    echo "======= Configuring ZFSBootMenu for auto-detection =========="
+    zfs set org.zfsbootmenu:commandline="ro quiet" "$ZFS_POOL/ROOT/debian"
+
+    echo "Boot configuration:"
+    zfs get org.zfsbootmenu:commandline "$ZFS_POOL/ROOT/debian"
+}
+
+# ---- System Services Functions ----
+function configure_system_services {
+    echo "======= Configuring ZFS cachefile in chrooted system =========="
+    mkdir -p "$TARGET/etc/zfs"
+    cp /etc/zfs/zpool.cache "$TARGET/etc/zfs/zpool.cache"
+
+    echo "Cachefile status:"
+    zpool get cachefile "$ZFS_POOL"
+    ls -la "$TARGET/etc/zfs/zpool.cache" && echo "✓ Cachefile ready" || echo "✗ Cachefile failed"
+
+    echo "======= Enabling essential system services =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+
+systemctl enable systemd-resolved
+systemctl enable systemd-timesyncd
+systemctl enable systemd-networkd
+
+systemctl enable zfs-import-cache
+systemctl enable zfs-mount
+
+systemctl enable ssh
+systemctl enable apt-daily.timer
+
+echo "Enabled services:"
+systemctl list-unit-files | grep enabled
+EOF
+}
+
+function configure_networking {
+    echo "======= Configuring systemd-networkd for Hetzner Cloud =========="
+    
+    # Create systemd-networkd configuration for all ethernet interfaces
+    mkdir -p "$TARGET/etc/systemd/network"
+    
+    cat > "$TARGET/etc/systemd/network/10-hetzner.network" <<'EOF'
+[Match]
+Name=ens* enp* eth*
+
+[Network]
+DHCP=yes
+IPv6PrivacyExtensions=yes
+
+[DHCP]
+RouteMetric=100
+UseDNS=yes
+UseDomains=yes
+
+[DHCPv4]
+RouteMetric=100
+UseDNS=yes
+UseDomains=yes
+
+[IPv6AcceptRA]
+RouteMetric=100
+EOF
+
+    echo "systemd-networkd configuration:"
+    cat "$TARGET/etc/systemd/network/10-hetzner.network"
+    echo ""
+}
+
+# ---- Cleanup and Finalization Functions ----
+function unmount_all_datasets_and_partitions {
+    echo "======= Unmounting all datasets =========="
+    
+    # First, unmount virtual filesystems that might be using the datasets
+    echo "Unmounting virtual filesystems..."
+    for dir in dev/pts dev tmp run/lock run/shm run sys proc; do
+        if mountpoint -q "$TARGET/$dir"; then
+            echo "Unmounting $TARGET/$dir"
+            umount "$TARGET/$dir" 2>/dev/null || true
+        fi
+    done
+    
+    # Give it a moment
+    sleep 2
+    
+    # Try to unmount boot partition first
+    if mountpoint -q "$MAIN_BOOT"; then
+        echo "Unmounting boot partition from $MAIN_BOOT"
+        umount "$MAIN_BOOT" 2>/dev/null || true
+    fi
+    
+    # Unmount ZFS datasets
+    echo "Unmounting ZFS datasets..."
+    zfs umount -a 2>/dev/null || true
+    
+    # Wait for unmounts to complete
+    sleep 2
+    
+    # If root dataset is still mounted, try lazy unmount
+    if mountpoint -q "$TARGET"; then
+        echo "Attempting lazy unmount of $TARGET"
+        umount -l "$TARGET" 2>/dev/null || true
+    fi
+    
+    # Force unmount any stubborn ZFS datasets
+    if zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep -q "yes"; then
+        echo "Forcing unmount of remaining ZFS datasets..."
+        zfs umount -a -f 2>/dev/null || true
+    fi
+    
+    # Final verification and force unmount if still mounted
+    if mountpoint -q "$TARGET"; then
+        echo "WARNING: $TARGET is still mounted! Attempting final cleanup..."
+        # Use fuser to find what's using the mount
+        if command -v fuser &> /dev/null; then
+            fuser -mv "$TARGET" 2>/dev/null || true
+        fi
+        # Force lazy unmount as last resort
+        umount -l "$TARGET" 2>/dev/null || true
+    fi
+    
+    # Final ZFS unmount check
+    local mounted_count=0
+    mounted_count=$(zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep -c "yes" || true)
+    
+    if [ "$mounted_count" -gt 0 ]; then
+        echo "WARNING: $mounted_count dataset(s) still mounted:"
+        zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep "yes" || true
+    else
+        echo "✓ All ZFS datasets successfully unmounted"
+    fi
+    
+    # Verify $TARGET is unmounted
+    if mountpoint -q "$TARGET"; then
+        echo "WARNING: $TARGET is still mounted but continuing..."
+    else
+        echo "✓ $TARGET successfully unmounted"
+    fi
+    
+    # Verify $MAIN_BOOT is unmounted
+    if mountpoint -q "$MAIN_BOOT"; then
+        echo "WARNING: $MAIN_BOOT is still mounted!"
+    else
+        echo "✓ $MAIN_BOOT successfully unmounted"
+    fi
+}
+
+function unmount_chroot_environment {
+    echo "======= Unmounting virtual filesystems =========="
+    # Unmount virtual filesystems first
+    for dir in dev/pts dev tmp run sys proc; do
+        if mountpoint -q "$TARGET/$dir"; then
+            echo "Unmounting $TARGET/$dir"
+            umount "$TARGET/$dir" 2>/dev/null || true
+        fi
+    done
+}
+
+function export_zfs_pool {
+    echo "======= Exporting ZFS pool =========="
+    # Export the pool to ensure clean state
+    zpool export "$ZFS_POOL"
+    echo "✓ ZFS pool '$ZFS_POOL' exported successfully"
+}
+
+function show_final_instructions {
+    echo ""
+    echo "=========================================="
+    echo "  INSTALLATION COMPLETE! "
+    echo "=========================================="
+    echo ""
+    echo "System Information:"
+    echo "  Hostname: $SYSTEM_HOSTNAME"
+    echo "  ZFS Pool: $ZFS_POOL"
+    echo "  Boot Mode: $([ "$EFI_MODE" = true ] && echo "EFI" || echo "BIOS")"
+    echo "  Debian Version: $DEBIAN_CODENAME"
+    echo "  Networking: systemd-networkd + systemd-resolved"
+    echo ""
+    echo "=========================================="
+    echo "Rebooting..."
+}
+
+# ---- Main Installation Flow ----
+function main {
+    echo "Starting ZFS Debian 13 installation on Hetzner..."
+    
+    # Get user input first
+    get_user_input
+    
+    # System detection
+    detect_efi
+    find_install_disk
+    
+    # Show summary and get confirmation
+    show_summary_and_confirm
+    
+    # Rescue system preparation
+    remove_unused_kernels
+    install_zfs_on_rescue_system
+    
+    # Disk partitioning
+    partition_disk
+    
+    # ZFS setup
+    create_zfs_pool
+    
+    # System installation
+    bootstrap_debian_system
+    setup_chroot_environment
+    configure_basic_system
+    install_system_packages
+    
+    verify_initramfs
+    configure_ssh
+    set_root_credentials
+    
+    # System configuration
+    configure_system_services
+    configure_networking
+    
+    # Bootloader configuration
+    configure_bootloader
+    
+    # Finalization
+    unmount_chroot_environment
+   
+    unmount_all_datasets_and_partitions
+    set_final_mountpoints
+    export_zfs_pool
+    
+    # Completion
+    show_final_instructions
+    
+    reboot
+}
+
+# Run main function
+main

hetzner-ubuntu18-zfs-setup.sh

@@ -17,6 +17,8 @@ set -o errexit
 set -o pipefail
 set -o nounset
 
+export TMPDIR=/tmp
+
 # Variables
 v_bpool_name=
 v_bpool_tweaks=
@@ -40,7 +42,7 @@ c_deb_security_repo=http://mirror.hetzner.de/ubuntu/security
 
 c_default_zfs_arc_max_mb=250
 c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
-c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=lz4 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
 c_default_hostname=terem
 c_zfs_mount_dir=/mnt
 c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
@@ -62,7 +64,9 @@ function print_step_info_header {
 ###############################################################################
 # ${FUNCNAME[1]}"
 
-  [[ "${1:-}" != "" ]] && echo -n " $1" || true
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
 
   echo "
 ###############################################################################
@@ -106,7 +110,7 @@ This script will prepare the ZFS pools, then install and configure minimal Ubunt
 The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
 In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
 '
-  dialog --ascii-lines --msgbox "$dialog_message" 30 100
+  dialog --msgbox "$dialog_message" 30 100
 }
 
 function store_os_distro_information {
@@ -173,9 +177,9 @@ LOG
   if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
     local dialog_message='No suitable disks have been found!
 
-If you think this is a bug, please open an issue on https://github.com/andrey42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
 '
-    dialog --ascii-lines --msgbox "$dialog_message" 30 100
+    dialog --msgbox "$dialog_message" 30 100
 
     exit 1
   fi
@@ -204,7 +208,7 @@ function select_disks {
 
 Devices with mounted partitions, cdroms, and removable devices are not displayed!
 "
-    mapfile -t v_selected_disks < <(dialog --ascii-lines --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
 
     if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
       break
@@ -221,7 +225,7 @@ function ask_swap_size {
   local swap_size_invalid_message=
 
   while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
-    v_swap_size=$(dialog --ascii-lines --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
 
     swap_size_invalid_message="Invalid swap size! "
   done
@@ -236,7 +240,7 @@ function ask_free_tail_space {
   local tail_space_invalid_message=
 
   while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
-    v_free_tail_space=$(dialog --ascii-lines --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
 
     tail_space_invalid_message="Invalid size! "
   done
@@ -251,7 +255,7 @@ function ask_zfs_arc_max_size {
   local zfs_arc_max_invalid_message=
 
   while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
-    v_zfs_arc_max_mb=$(dialog --ascii-lines --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
 
     zfs_arc_max_invalid_message="Invalid size! "
   done
@@ -267,14 +271,14 @@ function ask_pool_names {
   local bpool_name_invalid_message=
 
   while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_bpool_name=$(dialog --ascii-lines --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
 
     bpool_name_invalid_message="Invalid pool name! "
   done
   local rpool_name_invalid_message=
 
   while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_rpool_name=$(dialog --ascii-lines --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
 
     rpool_name_invalid_message="Invalid pool name! "
   done
@@ -286,8 +290,8 @@ function ask_pool_tweaks {
   # shellcheck disable=SC2119
   print_step_info_header
 
-  v_bpool_tweaks=$(dialog --ascii-lines --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
-  v_rpool_tweaks=$(dialog --ascii-lines --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
 
   print_variables v_bpool_tweaks v_rpool_tweaks
 }
@@ -302,8 +306,8 @@ function ask_root_password {
   local password_repeat=-
 
   while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
-    v_root_password=$(dialog --ascii-lines --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
-    password_repeat=$(dialog --ascii-lines --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
 
     password_invalid_message="Passphrase empty, or not matching! "
   done
@@ -313,7 +317,7 @@ function ask_root_password {
 function ask_encryption {
   print_step_info_header
 
-  if dialog --ascii-lines --yesno 'Do you want to encrypt the root pool?' 30 100; then
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
     v_encrypt_rpool=1
   fi
   set +x
@@ -321,8 +325,8 @@ function ask_encryption {
     local passphrase_invalid_message=
     local passphrase_repeat=-
     while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
-      v_passphrase=$(dialog --ascii-lines --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
-      passphrase_repeat=$(dialog --ascii-lines --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
 
       passphrase_invalid_message="Passphrase too short, or not matching! "
     done
@@ -333,7 +337,7 @@ function ask_encryption {
 function ask_zfs_experimental {
   print_step_info_header
 
-  if dialog --ascii-lines --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
     v_zfs_experimental=1
   fi
 }
@@ -344,8 +348,8 @@ function ask_hostname {
 
   local hostname_invalid_message=
 
-  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
-    v_hostname=$(dialog --ascii-lines --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
 
     hostname_invalid_message="Invalid host name! "
   done
@@ -362,7 +366,7 @@ function determine_kernel_variant {
 }
 
 function chroot_execute {
-  chroot $c_zfs_mount_dir bash -c "$1"
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
 }
 
 function unmount_and_export_fs {
@@ -399,8 +403,8 @@ function unmount_and_export_fs {
   echo "===========exporting zfs pools============="
   set +e
   while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do
-    zpool export -a 2> /dev/null
-    if [[ $? == 0 ]]; then
+    
+    if zpool export -a 2> /dev/null; then
       zpools_exported=1
       echo "all zfs pools were succesfully exported"
       break;
@@ -417,6 +421,7 @@ function unmount_and_export_fs {
 
 #################### MAIN ################################
 export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
 
 check_prerequisites
 
@@ -457,11 +462,20 @@ for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" |
 done
 
 echo "======= installing zfs on rescue system =========="
-  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
-
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
   apt update
-  apt install --yes -t buster-backports libelf-dev zfs-dkms
-  modprobe zfs
+  export PATH=$PATH:/usr/sbin
   zfs --version
 
 echo "======= partitioning the disk =========="
@@ -473,9 +487,9 @@ echo "======= partitioning the disk =========="
   fi
 
   for selected_disk in "${v_selected_disks[@]}"; do
-    wipefs --all "$selected_disk"
+    wipefs --all --force "$selected_disk"
     sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
-    sgdisk -n2:0:+512M                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
     sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
   done
 
@@ -502,13 +516,17 @@ echo "======= create zfs pools and datasets =========="
     pools_mirror_option=
   fi
 
+# shellcheck disable=SC2086
 zpool create \
   $v_bpool_tweaks -O canmount=off -O devices=off \
+  -o cachefile=/etc/zpool.cache \
   -O mountpoint=/boot -R $c_zfs_mount_dir -f \
   $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
 
+# shellcheck disable=SC2086
 echo -n "$v_passphrase" | zpool create \
   $v_rpool_tweaks \
+  -o cachefile=/etc/zpool.cache \
   "${encryption_options[@]}" \
   -O mountpoint=/ -R $c_zfs_mount_dir -f \
   $v_rpool_name $pools_mirror_option "${rpool_disks_partitions[@]}"
@@ -523,9 +541,7 @@ zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/ubuntu"
 zfs mount "$v_bpool_name/BOOT/ubuntu"
 
 zfs create                                 "$v_rpool_name/home"
-zfs create -o mountpoint=/root             "$v_rpool_name/home/root"
 zfs create -o canmount=off                 "$v_rpool_name/var"
-zfs create -o canmount=off                 "$v_rpool_name/var/lib"
 zfs create                                 "$v_rpool_name/var/log"
 zfs create                                 "$v_rpool_name/var/spool"
 
@@ -576,7 +592,7 @@ ff02::2 ip6-allrouters
 ff02::3 ip6-allhosts
 CONF
 
-ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p')
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
 
 cat <<CONF > /mnt/etc/systemd/network/10-eth0.network
 [Match]
@@ -589,7 +605,9 @@ Gateway=fe80::1
 CONF
 
 chroot_execute "systemctl enable systemd-networkd.service"
+chroot_execute "systemctl enable systemd-resolved.service"
 
+#cp /etc/resolv.conf $c_zfs_mount_dir/etc/resolv.conf
 
 mkdir -p "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/"
 cat > "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg" <<CONF
@@ -599,7 +617,6 @@ CONF
 
 rm -rf $c_zfs_mount_dir/etc/network/interfaces.d/50-cloud-init.cfg
 
-cp /etc/resolv.conf $c_zfs_mount_dir/etc/resolv.conf
 
 echo "======= preparing the jail for chroot =========="
 for virtual_fs_dir in proc sys dev; do
@@ -618,7 +635,7 @@ CONF
 chroot_execute "apt update"
 
 echo "======= setting locale, console and language =========="
-chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils"
+chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils keyboard-configuration console-setup"
 sed -i 's/# en_US.UTF-8/en_US.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
 sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
 sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
@@ -660,7 +677,6 @@ CONF'
 
 chroot_execute "dpkg-reconfigure locales -f noninteractive"
 echo -e "LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8\n" >> "$c_zfs_mount_dir/etc/environment"
-chroot_execute "apt install -qq --yes keyboard-configuration console-setup"
 chroot_execute "dpkg-reconfigure keyboard-configuration -f noninteractive"
 chroot_execute "dpkg-reconfigure console-setup -f noninteractive"
 chroot_execute "setupcon"
@@ -669,32 +685,35 @@ chroot_execute "rm -f /etc/localtime /etc/timezone"
 chroot_execute "dpkg-reconfigure tzdata -f noninteractive "
 
 echo "======= installing latest kernel============="
-chroot_execute "DEBIAN_FRONTEND=noninteractive apt install --yes linux-headers${v_kernel_variant}-hwe-18.04 linux-image${v_kernel_variant}-hwe-18.04"
+chroot_execute "apt install --yes linux-headers${v_kernel_variant}-hwe-18.04 linux-image${v_kernel_variant}-hwe-18.04"
 if [[ $v_kernel_variant == "-virtual" ]]; then
   # linux-image-extra is only available for virtual hosts
-  chroot_execute "DEBIAN_FRONTEND=noninteractive apt install --yes linux-image-extra-virtual-hwe-18.04"
+  chroot_execute "apt install --yes linux-image-extra-virtual-hwe-18.04"
 fi
 
-
 echo "======= installing aux packages =========="
 chroot_execute "apt install --yes man wget curl software-properties-common nano htop gnupg"
 chroot_execute "systemctl disable thermald"
 
 echo "======= installing zfs packages =========="
-if [[ $v_zfs_experimental == "1" ]]; then
-  chroot_execute "wget -O - https://andrey42.github.io/zfs-ubuntu/apt_pub.gpg | apt-key add -"
-  chroot_execute "add-apt-repository 'deb https://andrey42.github.io/zfs-ubuntu/public zfs-debian-experimental main'"
-  chroot_execute "apt update"
-else
-  chroot_execute "add-apt-repository --yes ppa:jonathonf/zfs"
-fi
 chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
 
 if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
   chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
 else
+  chroot_execute "add-apt-repository --yes ppa:jonathonf/zfs"
   chroot_execute "apt install --yes zfs-initramfs zfs-dkms zfsutils-linux"
 fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
 echo "======= installing OpenSSH and network tooling =========="
 chroot_execute "apt install --yes openssh-server net-tools"
 
@@ -709,37 +728,22 @@ chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
 echo "======= set root password =========="
 chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
 
-echo "======= setting up zfs services =========="
-chroot_execute "cat > /etc/systemd/system/zfs-import-bpool.service <<UNIT
-[Unit]
-DefaultDependencies=no
-Before=zfs-import-scan.service
-Before=zfs-import-cache.service
-
-[Service]
-Type=oneshot
-RemainAfterExit=yes
-ExecStartPre=/bin/sh -c '[ -f /etc/zfs/zpool.cache ] && mv /etc/zfs/zpool.cache /etc/zfs/preboot_zpool.cache || true'
-ExecStart=/sbin/zpool import -N -o cachefile=none $v_bpool_name
-ExecStartPost=/bin/sh -c '[ -f /etc/zfs/preboot_zpool.cache ] && mv /etc/zfs/preboot_zpool.cache /etc/zfs/zpool.cache || true'
-
-[Install]
-WantedBy=zfs-import.target
-UNIT"
-
-chroot_execute "systemctl enable zfs-import-bpool.service"
+echo "======= setting up zfs cache =========="
+cp /etc/zpool.cache /mnt/etc/zfs/zpool.cache
 
 echo "========setting up zfs module parameters========"
 chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
 
 echo "======= setting up grub =========="
 chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
-chroot_execute "DEBIAN_FRONTEND=noninteractive apt install --yes grub-pc"
-chroot_execute "grub-install ${v_selected_disks[0]}"
+chroot_execute "apt install --yes grub-pc"
+for disk in ${v_selected_disks[@]}; do
+  chroot_execute "grub-install $disk"
+done
 
 chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
 chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
-chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=rpool/ROOT/ubuntu\"|g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/ubuntu\"|g' /etc/default/grub"
 
 chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
 chroot_execute "sed -i 's/splash//g' /etc/default/grub"
@@ -767,18 +771,6 @@ if [[ $v_encrypt_rpool == "1" ]]; then
   rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
 
   rm -rf "$c_zfs_mount_dir/etc/dropbear-initramfs/dropbear_dss_host_key"
-
-  cd "$c_zfs_mount_dir/root"
-  wget http://ftp.de.debian.org/debian/pool/main/libt/libtommath/libtommath1_1.1.0-3_amd64.deb
-  wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-bin_2018.76-5_amd64.deb
-  wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-initramfs_2018.76-5_all.deb
-
-  chroot_execute "dpkg -i /root/libtommath1_1.1.0-3_amd64.deb"
-  chroot_execute "dpkg -i /root/dropbear-bin_2018.76-5_amd64.deb"
-  chroot_execute "dpkg -i /root/dropbear-initramfs_2018.76-5_all.deb"
-
-  rm $c_zfs_mount_dir/root/*.deb
-  cd /root
 fi
 
 echo "============setup root prompt============"
@@ -791,6 +783,7 @@ CONF
 
 echo "========running packages upgrade==========="
 chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
 
 echo "===========add static route to initramfs via hook to add default routes due to Ubuntu initramfs DHCP bug ========="
 mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
@@ -814,8 +807,8 @@ esac
 
 configure_networking
 
-ip route add 172.31.1.1/255.255.255.255 dev ens3
-ip route add default via 172.31.1.1 dev ens3
+ip route add 172.31.1.1/255.255.255.255 dev eth0
+ip route add default via 172.31.1.1 dev eth0
 CONF
 
 chmod 755 "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route"
@@ -828,11 +821,11 @@ chroot_execute "update-grub"
 
 echo "======= setting up zed =========="
 
-chroot_execute "zfs set canmount=noauto rpool"
+chroot_execute "zfs set canmount=noauto $v_rpool_name"
 
 echo "======= setting mountpoints =========="
 chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/ubuntu"
-chroot_execute "echo $v_bpool_name/BOOT/ubuntu /boot zfs nodev,relatime,x-systemd.requires=zfs-import-bpool.service 0 0 > /etc/fstab"
+chroot_execute "echo $v_bpool_name/BOOT/ubuntu /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
 
 chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
 chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
@@ -844,7 +837,10 @@ chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
 chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
 
 echo "========= add swap, if defined"
-[[ $v_swap_size -gt 0 ]] && chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab" || true
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
+
 chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
 
 echo "======= unmounting filesystems and zfs pools =========="

hetzner-ubuntu20-zfs-setup.sh

@@ -0,0 +1,863 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Ubuntu 20 LTS with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, set it OS to linux64, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname and ZFS ARC cache size
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -o errexit
+set -o pipefail
+set -o nounset
+
+export TMPDIR=/tmp
+
+# Variables
+v_bpool_name=
+v_bpool_tweaks=
+v_rpool_name=
+v_rpool_tweaks=
+declare -a v_selected_disks
+v_swap_size=                 # integer
+v_free_tail_space=           # integer
+v_hostname=
+v_kernel_variant=
+v_zfs_arc_max_mb=
+v_root_password=
+v_encrypt_rpool=             # 0=false, 1=true
+v_passphrase=
+v_zfs_experimental=
+v_suitable_disks=()
+
+# Constants
+c_deb_packages_repo=http://mirror.hetzner.de/ubuntu/packages
+c_deb_security_repo=http://mirror.hetzner.de/ubuntu/security
+
+c_default_zfs_arc_max_mb=250
+c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_hostname=terem
+c_zfs_mount_dir=/mnt
+c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
+c_install_log=$c_log_dir/install.log
+c_lsb_release_log=$c_log_dir/lsb_release.log
+c_disks_log=$c_log_dir/disks.log
+
+function activate_debug {
+  mkdir -p "$c_log_dir"
+
+  exec 5> "$c_install_log"
+  BASH_XTRACEFD="5"
+  set -x
+}
+
+# shellcheck disable=SC2120
+function print_step_info_header {
+  echo -n "
+###############################################################################
+# ${FUNCNAME[1]}"
+
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
+
+  echo "
+###############################################################################
+"
+}
+
+function print_variables {
+  for variable_name in "$@"; do
+    declare -n variable_reference="$variable_name"
+
+    echo -n "$variable_name:"
+
+    case "$(declare -p "$variable_name")" in
+    "declare -a"* )
+      for entry in "${variable_reference[@]}"; do
+        echo -n " \"$entry\""
+      done
+      ;;
+    "declare -A"* )
+      for key in "${!variable_reference[@]}"; do
+        echo -n " $key=\"${variable_reference[$key]}\""
+      done
+      ;;
+    * )
+      echo -n " $variable_reference"
+      ;;
+    esac
+
+    echo
+  done
+
+  echo
+}
+
+function display_intro_banner {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local dialog_message='Hello!
+This script will prepare the ZFS pools, then install and configure minimal Ubuntu 20 LTS with ZFS root on Hetzner hosting VPS instance
+The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
+In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
+'
+  dialog --msgbox "$dialog_message" 30 100
+}
+
+function store_os_distro_information {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  lsb_release --all > "$c_lsb_release_log"
+}
+
+function check_prerequisites {
+  # shellcheck disable=SC2119
+  print_step_info_header
+  if [[ $(id -u) -ne 0 ]]; then
+    echo 'This script must be run with administrative privileges!'
+    exit 1
+  fi
+  if [[ ! -r /root/.ssh/authorized_keys ]]; then
+    echo "SSH pubkey file is absent, please add it to the rescue system setting, then reboot into rescue system and run the script"
+    exit 1
+  fi
+  if ! dpkg-query --showformat="\${Status}" -W dialog 2> /dev/null | grep -q "install ok installed"; then
+    apt install --yes dialog
+  fi
+}
+
+
+function find_suitable_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  udevadm trigger
+
+  # shellcheck disable=SC2012
+  ls -l /dev/disk/by-id | tail -n +2 | perl -lane 'print "@F[8..10]"' > "$c_disks_log"
+
+  local candidate_disk_ids
+  local mounted_devices
+
+  candidate_disk_ids=$(find /dev/disk/by-id -regextype awk -regex '.+/(ata|nvme|scsi)-.+' -not -regex '.+-part[0-9]+$' | sort)
+  mounted_devices="$(df | awk 'BEGIN {getline} {print $1}' | xargs -n 1 lsblk -no pkname 2> /dev/null | sort -u || true)"
+
+  while read -r disk_id || [[ -n "$disk_id" ]]; do
+    local device_info
+
+    device_info="$(udevadm info --query=property "$(readlink -f "$disk_id")")"
+    block_device_basename="$(basename "$(readlink -f "$disk_id")")"
+
+    if ! grep -q '^ID_TYPE=cd$' <<< "$device_info"; then
+      if ! grep -q "^$block_device_basename\$" <<< "$mounted_devices"; then
+        v_suitable_disks+=("$disk_id")
+      fi
+    fi
+
+    cat >> "$c_disks_log" << LOG
+
+## DEVICE: $disk_id ################################
+
+$(udevadm info --query=property "$(readlink -f "$disk_id")")
+
+LOG
+
+  done < <(echo -n "$candidate_disk_ids")
+
+  if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
+    local dialog_message='No suitable disks have been found!
+
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+'
+    dialog --msgbox "$dialog_message" 30 100
+
+    exit 1
+  fi
+
+  print_variables v_suitable_disks
+}
+
+function select_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  while true; do
+    local menu_entries_option=()
+
+    if [[ ${#v_suitable_disks[@]} -eq 1 ]]; then
+      local disk_selection_status=ON
+    else
+      local disk_selection_status=OFF
+    fi
+
+    for disk_id in "${v_suitable_disks[@]}"; do
+      menu_entries_option+=("$disk_id" "($block_device_basename)" "$disk_selection_status")
+    done
+
+    local dialog_message="Select the ZFS devices (multiple selections will be in mirror).
+
+Devices with mounted partitions, cdroms, and removable devices are not displayed!
+"
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+
+    if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
+      break
+    fi
+  done
+
+  print_variables v_selected_disks
+}
+
+function ask_swap_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local swap_size_invalid_message=
+
+  while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+
+    swap_size_invalid_message="Invalid swap size! "
+  done
+
+  print_variables v_swap_size
+}
+
+function ask_free_tail_space {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local tail_space_invalid_message=
+
+  while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+
+    tail_space_invalid_message="Invalid size! "
+  done
+
+  print_variables v_free_tail_space
+}
+
+function ask_zfs_arc_max_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local zfs_arc_max_invalid_message=
+
+  while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+
+    zfs_arc_max_invalid_message="Invalid size! "
+  done
+
+  print_variables v_zfs_arc_max_mb
+}
+
+
+function ask_pool_names {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local bpool_name_invalid_message=
+
+  while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+
+    bpool_name_invalid_message="Invalid pool name! "
+  done
+  local rpool_name_invalid_message=
+
+  while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+
+    rpool_name_invalid_message="Invalid pool name! "
+  done
+
+  print_variables v_bpool_name v_rpool_name
+}
+
+function ask_pool_tweaks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+
+  print_variables v_bpool_tweaks v_rpool_tweaks
+}
+
+
+function ask_root_password {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  set +x
+  local password_invalid_message=
+  local password_repeat=-
+
+  while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+
+    password_invalid_message="Passphrase empty, or not matching! "
+  done
+  set -x
+}
+
+function ask_encryption {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
+    v_encrypt_rpool=1
+  fi
+  set +x
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    local passphrase_invalid_message=
+    local passphrase_repeat=-
+    while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+
+      passphrase_invalid_message="Passphrase too short, or not matching! "
+    done
+  fi
+  set -x
+}
+
+function ask_zfs_experimental {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+    v_zfs_experimental=1
+  fi
+}
+
+function ask_hostname {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local hostname_invalid_message=
+
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+
+    hostname_invalid_message="Invalid host name! "
+  done
+
+  print_variables v_hostname
+}
+
+function determine_kernel_variant {
+  if dmidecode | grep -q vServer; then
+    v_kernel_variant="-virtual"
+  else
+    v_kernel_variant="-generic"
+  fi
+}
+
+function chroot_execute {
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
+}
+
+function unmount_and_export_fs {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  for virtual_fs_dir in dev sys proc; do
+    umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+  done
+
+  local max_unmount_wait=5
+  echo -n "Waiting for virtual filesystems to unmount "
+
+  SECONDS=0
+
+  for virtual_fs_dir in dev sys proc; do
+    while mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir" && [[ $SECONDS -lt $max_unmount_wait ]]; do
+      sleep 0.5
+      echo -n .
+    done
+  done
+
+  echo
+
+  for virtual_fs_dir in dev sys proc; do
+    if mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir"; then
+      echo "Re-issuing umount for $c_zfs_mount_dir/$virtual_fs_dir"
+      umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+    fi
+  done
+
+  SECONDS=0
+  zpools_exported=99
+  echo "===========exporting zfs pools============="
+  set +e
+  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do
+    
+    if zpool export -a 2> /dev/null; then
+      zpools_exported=1
+      echo "all zfs pools were succesfully exported"
+      break;
+    else
+      sleep 1
+     fi
+  done
+  set -e
+  if (( zpools_exported != 1 )); then
+    echo "failed to export zfs pools"
+    exit 1
+  fi
+}
+
+#################### MAIN ################################
+export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
+
+check_prerequisites
+
+display_intro_banner
+
+activate_debug
+
+find_suitable_disks
+
+select_disks
+
+ask_swap_size
+
+ask_free_tail_space
+
+ask_pool_names
+
+ask_pool_tweaks
+
+ask_encryption
+
+ask_zfs_arc_max_size
+
+ask_zfs_experimental
+
+ask_root_password
+
+ask_hostname
+
+determine_kernel_variant
+
+clear
+
+echo "===========remove unused kernels in rescue system========="
+for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" | cut -s -d "/" -f 4); do
+  apt purge --yes "linux-headers-$kver"
+  apt purge --yes "linux-image-$kver"
+done
+
+echo "======= installing zfs on rescue system =========="
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
+  apt update
+  export PATH=$PATH:/usr/sbin
+  zfs --version
+
+echo "======= partitioning the disk =========="
+
+  if [[ $v_free_tail_space -eq 0 ]]; then
+    tail_space_parameter=0
+  else
+    tail_space_parameter="-${v_free_tail_space}G"
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    wipefs --all --force "$selected_disk"
+    sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
+  done
+
+  udevadm settle
+
+echo "======= create zfs pools and datasets =========="
+
+  encryption_options=()
+  rpool_disks_partitions=()
+  bpool_disks_partitions=()
+
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    encryption_options=(-O "encryption=aes-256-gcm" -O "keylocation=prompt" -O "keyformat=passphrase")
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    rpool_disks_partitions+=("${selected_disk}-part3")
+    bpool_disks_partitions+=("${selected_disk}-part2")
+  done
+
+  if [[ ${#v_selected_disks[@]} -gt 1 ]]; then
+    pools_mirror_option=mirror
+  else
+    pools_mirror_option=
+  fi
+
+# shellcheck disable=SC2086
+zpool create \
+  $v_bpool_tweaks -O canmount=off -O devices=off \
+  -o cachefile=/etc/zpool.cache \
+  -O mountpoint=/boot -R $c_zfs_mount_dir -f \
+  $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
+
+# shellcheck disable=SC2086
+echo -n "$v_passphrase" | zpool create \
+  $v_rpool_tweaks \
+  -o cachefile=/etc/zpool.cache \
+  "${encryption_options[@]}" \
+  -O mountpoint=/ -R $c_zfs_mount_dir -f \
+  $v_rpool_name $pools_mirror_option "${rpool_disks_partitions[@]}"
+
+zfs create -o canmount=off -o mountpoint=none "$v_rpool_name/ROOT"
+zfs create -o canmount=off -o mountpoint=none "$v_bpool_name/BOOT"
+
+zfs create -o canmount=noauto -o mountpoint=/ "$v_rpool_name/ROOT/ubuntu"
+zfs mount "$v_rpool_name/ROOT/ubuntu"
+
+zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/ubuntu"
+zfs mount "$v_bpool_name/BOOT/ubuntu"
+
+zfs create                                 "$v_rpool_name/home"
+zfs create -o canmount=off                 "$v_rpool_name/var"
+zfs create                                 "$v_rpool_name/var/log"
+zfs create                                 "$v_rpool_name/var/spool"
+
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/cache"
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/tmp"
+chmod 1777 "$c_zfs_mount_dir/var/tmp"
+
+zfs create                                 "$v_rpool_name/srv"
+
+zfs create -o canmount=off                 "$v_rpool_name/usr"
+zfs create                                 "$v_rpool_name/usr/local"
+
+zfs create                                 "$v_rpool_name/var/mail"
+
+zfs create -o com.sun:auto-snapshot=false -o canmount=on -o mountpoint=/tmp "$v_rpool_name/tmp"
+chmod 1777 "$c_zfs_mount_dir/tmp"
+
+if [[ $v_swap_size -gt 0 ]]; then
+  zfs create \
+    -V "${v_swap_size}G" -b "$(getconf PAGESIZE)" \
+    -o compression=zle -o logbias=throughput -o sync=always -o primarycache=metadata -o secondarycache=none -o com.sun:auto-snapshot=false \
+    "$v_rpool_name/swap"
+
+  udevadm settle
+
+  mkswap -f "/dev/zvol/$v_rpool_name/swap"
+fi
+
+echo "======= setting up initial system packages =========="
+debootstrap --arch=amd64 focal "$c_zfs_mount_dir" "$c_deb_packages_repo"
+
+zfs set devices=off "$v_rpool_name"
+
+echo "======= setting up the network =========="
+
+echo "$v_hostname" > $c_zfs_mount_dir/etc/hostname
+
+cat > "$c_zfs_mount_dir/etc/hosts" <<CONF
+127.0.1.1 ${v_hostname}
+127.0.0.1 localhost
+
+# The following lines are desirable for IPv6 capable hosts
+::1 ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+CONF
+
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
+
+cat <<CONF > /mnt/etc/systemd/network/10-eth0.network
+[Match]
+Name=eth0
+
+[Network]
+DHCP=ipv4
+Address=${ip6addr_prefix}:1/64
+Gateway=fe80::1
+CONF
+
+chroot_execute "systemctl enable systemd-networkd.service"
+chroot_execute "systemctl enable systemd-resolved.service"
+
+
+mkdir -p "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/"
+cat > "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg" <<CONF
+network:
+  config: disabled
+CONF
+
+rm -rf $c_zfs_mount_dir/etc/network/interfaces.d/50-cloud-init.cfg
+
+#cp /etc/resolv.conf $c_zfs_mount_dir/etc/resolv.conf
+
+echo "======= preparing the jail for chroot =========="
+for virtual_fs_dir in proc sys dev; do
+  mount --rbind "/$virtual_fs_dir" "$c_zfs_mount_dir/$virtual_fs_dir"
+done
+
+echo "======= setting apt repos =========="
+cat > "$c_zfs_mount_dir/etc/apt/sources.list" <<CONF
+deb [arch=i386,amd64] $c_deb_packages_repo focal main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo focal-updates main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo focal-backports main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo focal universe
+deb [arch=i386,amd64] $c_deb_security_repo focal-security main restricted
+CONF
+
+chroot_execute "apt update"
+
+echo "======= setting locale, console and language =========="
+chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils keyboard-configuration console-setup"
+sed -i 's/# en_US.UTF-8/en_US.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_AT.UTF-8/de_AT.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_DE.UTF-8/de_DE.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+
+chroot_execute 'cat <<CONF | debconf-set-selections
+locales locales/default_environment_locale      select  en_US.UTF-8
+keyboard-configuration  keyboard-configuration/store_defaults_in_debconf_db     boolean true
+keyboard-configuration  keyboard-configuration/variant  select  German
+keyboard-configuration  keyboard-configuration/unsupported_layout       boolean true
+keyboard-configuration  keyboard-configuration/modelcode        string  pc105
+keyboard-configuration  keyboard-configuration/unsupported_config_layout        boolean true
+keyboard-configuration  keyboard-configuration/layout   select  German
+keyboard-configuration  keyboard-configuration/layoutcode       string  de
+keyboard-configuration  keyboard-configuration/optionscode      string
+keyboard-configuration  keyboard-configuration/toggle   select  No toggling
+keyboard-configuration  keyboard-configuration/xkb-keymap       select  de
+keyboard-configuration  keyboard-configuration/switch   select  No temporary switch
+keyboard-configuration  keyboard-configuration/unsupported_config_options       boolean true
+keyboard-configuration  keyboard-configuration/ctrl_alt_bksp    boolean false
+keyboard-configuration  keyboard-configuration/variantcode      string
+keyboard-configuration  keyboard-configuration/model    select  Generic 105-key PC (intl.)
+keyboard-configuration  keyboard-configuration/altgr    select  The default for the keyboard layout
+keyboard-configuration  keyboard-configuration/compose  select  No compose key
+keyboard-configuration  keyboard-configuration/unsupported_options      boolean true
+console-setup   console-setup/fontsize-fb47     select  8x16
+console-setup   console-setup/store_defaults_in_debconf_db      boolean true
+console-setup   console-setup/codeset47 select  # Latin1 and Latin5 - western Europe and Turkic languages
+console-setup   console-setup/fontface47        select  Fixed
+console-setup   console-setup/fontsize  string  8x16
+console-setup   console-setup/charmap47 select  UTF-8
+console-setup   console-setup/fontsize-text47   select  8x16
+console-setup   console-setup/codesetcode       string  Lat15
+tzdata tzdata/Areas select Europe
+tzdata tzdata/Zones/Europe select Vienna
+grub-pc grub-pc/install_devices_empty   boolean true
+CONF'
+
+chroot_execute "dpkg-reconfigure locales -f noninteractive"
+echo -e "LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8\n" >> "$c_zfs_mount_dir/etc/environment"
+chroot_execute "dpkg-reconfigure keyboard-configuration -f noninteractive"
+chroot_execute "dpkg-reconfigure console-setup -f noninteractive"
+chroot_execute "setupcon"
+
+chroot_execute "rm -f /etc/localtime /etc/timezone"
+chroot_execute "dpkg-reconfigure tzdata -f noninteractive "
+
+echo "======= installing latest kernel============="
+chroot_execute "apt install --yes linux-headers${v_kernel_variant} linux-image${v_kernel_variant}"
+if [[ $v_kernel_variant == "-virtual" ]]; then
+  # linux-image-extra is only available for virtual hosts
+  chroot_execute "apt install --yes linux-image-extra-virtual"
+fi
+
+
+echo "======= installing aux packages =========="
+chroot_execute "apt install --yes man-db wget curl software-properties-common nano htop gnupg"
+chroot_execute "systemctl disable thermald"
+
+echo "======= installing zfs packages =========="
+chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
+
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
+  chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
+else
+  chroot_execute "add-apt-repository --yes ppa:jonathonf/zfs"
+  chroot_execute "apt install --yes zfs-initramfs zfs-dkms zfsutils-linux"
+fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
+echo "======= installing OpenSSH and network tooling =========="
+chroot_execute "apt install --yes openssh-server net-tools"
+
+echo "======= setup OpenSSH  =========="
+mkdir -p "$c_zfs_mount_dir/root/.ssh/"
+cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/root/.ssh/authorized_keys"
+sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+chroot_execute "rm /etc/ssh/ssh_host_*"
+chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
+
+echo "======= set root password =========="
+chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
+
+echo "======= setting up zfs cache =========="
+cp /etc/zpool.cache /mnt/etc/zfs/zpool.cache
+
+echo "========setting up zfs module parameters========"
+chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
+
+echo "======= setting up grub =========="
+chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
+chroot_execute "apt install --yes grub-pc"
+for disk in ${v_selected_disks[@]}; do
+  chroot_execute "grub-install $disk"
+done
+
+chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/ubuntu\"|g' /etc/default/grub"
+
+chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
+chroot_execute "sed -i 's/splash//g' /etc/default/grub"
+chroot_execute "echo 'GRUB_DISABLE_OS_PROBER=true'   >> /etc/default/grub"
+
+for ((i = 1; i < ${#v_selected_disks[@]}; i++)); do
+  dd if="${v_selected_disks[0]}-part1" of="${v_selected_disks[i]}-part1"
+done
+
+if [[ $v_encrypt_rpool == "1" ]]; then
+  echo "=========set up dropbear=============="
+  chroot_execute "apt install --yes dropbear-initramfs"
+  
+  cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/etc/dropbear-initramfs/authorized_keys"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_rsa_key_temp /etc/dropbear-initramfs/dropbear_rsa_host_key"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_ecdsa_key_temp /etc/dropbear-initramfs/dropbear_ecdsa_host_key"
+  chroot_execute "rm -rf /etc/ssh/ssh_host_ecdsa_key_temp"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+
+  rm -rf "$c_zfs_mount_dir/etc/dropbear-initramfs/dropbear_dss_host_key"
+
+  cd "$c_zfs_mount_dir/root"
+  wget http://ftp.de.debian.org/debian/pool/main/libt/libtommath/libtommath1_1.2.0-6_amd64.deb
+  wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-bin_2020.81-3_amd64.deb
+  wget http://ftp.de.debian.org/debian/pool/main/d/dropbear/dropbear-initramfs_2020.81-3_all.deb
+
+  chroot_execute "dpkg -i /root/libtommath1_1.2.0-6_amd64.deb"
+  chroot_execute "dpkg -i /root/dropbear-bin_2020.81-3_amd64.deb"
+  chroot_execute "dpkg -i /root/dropbear-initramfs_2020.81-3_all.deb"
+
+  rm $c_zfs_mount_dir/root/*.deb
+  cd /root
+fi
+
+echo "============setup root prompt============"
+cat > "$c_zfs_mount_dir/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+
+echo "========running packages upgrade==========="
+chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
+
+echo "===========add static route to initramfs via hook to add default routes due to Ubuntu initramfs DHCP bug ========="
+mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
+cat > "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route" <<'CONF'
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+    echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+
+. /scripts/functions
+# Begin real processing below this line
+
+configure_networking
+
+ip route add 172.31.1.1/255.255.255.255 dev ens3
+ip route add default via 172.31.1.1 dev ens3
+CONF
+
+chmod 755 "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route"
+
+echo "======= update initramfs =========="
+chroot_execute "update-initramfs -u -k all"
+
+echo "======= update grub =========="
+chroot_execute "update-grub"
+
+echo "======= setting up zed =========="
+
+chroot_execute "zfs set canmount=noauto $v_rpool_name"
+
+echo "======= setting mountpoints =========="
+chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/ubuntu"
+chroot_execute "echo $v_bpool_name/BOOT/ubuntu /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
+
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
+chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/spool"
+chroot_execute "echo $v_rpool_name/var/spool /var/spool zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/tmp"
+chroot_execute "echo $v_rpool_name/var/tmp /var/tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
+chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+
+echo "========= add swap, if defined"
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
+
+chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
+
+echo "======= unmounting filesystems and zfs pools =========="
+unmount_and_export_fs
+
+echo "======== setup complete, rebooting ==============="
+reboot

hetzner-ubuntu22-zfs-setup.sh

@@ -0,0 +1,852 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Ubuntu 20 LTS with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, set it OS to linux64, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname and ZFS ARC cache size
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -o errexit
+set -o pipefail
+set -o nounset
+
+export TMPDIR=/tmp
+
+# Variables
+v_bpool_name=
+v_bpool_tweaks=
+v_rpool_name=
+v_rpool_tweaks=
+declare -a v_selected_disks
+v_swap_size=                 # integer
+v_free_tail_space=           # integer
+v_hostname=
+v_kernel_variant=
+v_zfs_arc_max_mb=
+v_root_password=
+v_encrypt_rpool=             # 0=false, 1=true
+v_passphrase=
+v_zfs_experimental=
+v_suitable_disks=()
+
+# Constants
+c_deb_packages_repo=http://mirror.hetzner.de/ubuntu/packages
+c_deb_security_repo=http://mirror.hetzner.de/ubuntu/security
+
+c_default_zfs_arc_max_mb=250
+c_default_bpool_tweaks="-o ashift=12 -O compression=lz4"
+c_default_rpool_tweaks="-o ashift=12 -O acltype=posixacl -O compression=zstd-9 -O dnodesize=auto -O relatime=on -O xattr=sa -O normalization=formD"
+c_default_hostname=terem
+c_zfs_mount_dir=/mnt
+c_log_dir=$(dirname "$(mktemp)")/zfs-hetzner-vm
+c_install_log=$c_log_dir/install.log
+c_lsb_release_log=$c_log_dir/lsb_release.log
+c_disks_log=$c_log_dir/disks.log
+
+function activate_debug {
+  mkdir -p "$c_log_dir"
+
+  exec 5> "$c_install_log"
+  BASH_XTRACEFD="5"
+  set -x
+}
+
+# shellcheck disable=SC2120
+function print_step_info_header {
+  echo -n "
+###############################################################################
+# ${FUNCNAME[1]}"
+
+  if [[ "${1:-}" != "" ]]; then
+    echo -n " $1" 
+  fi
+
+  echo "
+###############################################################################
+"
+}
+
+function print_variables {
+  for variable_name in "$@"; do
+    declare -n variable_reference="$variable_name"
+
+    echo -n "$variable_name:"
+
+    case "$(declare -p "$variable_name")" in
+    "declare -a"* )
+      for entry in "${variable_reference[@]}"; do
+        echo -n " \"$entry\""
+      done
+      ;;
+    "declare -A"* )
+      for key in "${!variable_reference[@]}"; do
+        echo -n " $key=\"${variable_reference[$key]}\""
+      done
+      ;;
+    * )
+      echo -n " $variable_reference"
+      ;;
+    esac
+
+    echo
+  done
+
+  echo
+}
+
+function display_intro_banner {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local dialog_message='Hello!
+This script will prepare the ZFS pools, then install and configure minimal Ubuntu 20 LTS with ZFS root on Hetzner hosting VPS instance
+The script with minimal changes may be used on any other hosting provider  supporting KVM virtualization and offering Debian-based rescue system.
+In order to stop the procedure, hit Esc twice during dialogs (excluding yes/no ones), or Ctrl+C while any operation is running.
+'
+  dialog --msgbox "$dialog_message" 30 100
+}
+
+function store_os_distro_information {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  lsb_release --all > "$c_lsb_release_log"
+}
+
+function check_prerequisites {
+  # shellcheck disable=SC2119
+  print_step_info_header
+  if [[ $(id -u) -ne 0 ]]; then
+    echo 'This script must be run with administrative privileges!'
+    exit 1
+  fi
+  if [[ ! -r /root/.ssh/authorized_keys ]]; then
+    echo "SSH pubkey file is absent, please add it to the rescue system setting, then reboot into rescue system and run the script"
+    exit 1
+  fi
+  if ! dpkg-query --showformat="\${Status}" -W dialog 2> /dev/null | grep -q "install ok installed"; then
+    apt install --yes dialog
+  fi
+}
+
+
+function find_suitable_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  udevadm trigger
+
+  # shellcheck disable=SC2012
+  ls -l /dev/disk/by-id | tail -n +2 | perl -lane 'print "@F[8..10]"' > "$c_disks_log"
+
+  local candidate_disk_ids
+  local mounted_devices
+
+  candidate_disk_ids=$(find /dev/disk/by-id -regextype awk -regex '.+/(ata|nvme|scsi)-.+' -not -regex '.+-part[0-9]+$' | sort)
+  mounted_devices="$(df | awk 'BEGIN {getline} {print $1}' | xargs -n 1 lsblk -no pkname 2> /dev/null | sort -u || true)"
+
+  while read -r disk_id || [[ -n "$disk_id" ]]; do
+    local device_info
+
+    device_info="$(udevadm info --query=property "$(readlink -f "$disk_id")")"
+    block_device_basename="$(basename "$(readlink -f "$disk_id")")"
+
+    if ! grep -q '^ID_TYPE=cd$' <<< "$device_info"; then
+      if ! grep -q "^$block_device_basename\$" <<< "$mounted_devices"; then
+        v_suitable_disks+=("$disk_id")
+      fi
+    fi
+
+    cat >> "$c_disks_log" << LOG
+
+## DEVICE: $disk_id ################################
+
+$(udevadm info --query=property "$(readlink -f "$disk_id")")
+
+LOG
+
+  done < <(echo -n "$candidate_disk_ids")
+
+  if [[ ${#v_suitable_disks[@]} -eq 0 ]]; then
+    local dialog_message='No suitable disks have been found!
+
+If you think this is a bug, please open an issue on https://github.com/terem42/zfs-hetzner-vm/issues, and attach the file `'"$c_disks_log"'`.
+'
+    dialog --msgbox "$dialog_message" 30 100
+
+    exit 1
+  fi
+
+  print_variables v_suitable_disks
+}
+
+function select_disks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  while true; do
+    local menu_entries_option=()
+
+    if [[ ${#v_suitable_disks[@]} -eq 1 ]]; then
+      local disk_selection_status=ON
+    else
+      local disk_selection_status=OFF
+    fi
+
+    for disk_id in "${v_suitable_disks[@]}"; do
+      menu_entries_option+=("$disk_id" "($block_device_basename)" "$disk_selection_status")
+    done
+
+    local dialog_message="Select the ZFS devices (multiple selections will be in mirror).
+
+Devices with mounted partitions, cdroms, and removable devices are not displayed!
+"
+    mapfile -t v_selected_disks < <(dialog --separate-output --checklist "$dialog_message" 30 100 $((${#menu_entries_option[@]} / 3)) "${menu_entries_option[@]}" 3>&1 1>&2 2>&3)
+
+    if [[ ${#v_selected_disks[@]} -gt 0 ]]; then
+      break
+    fi
+  done
+
+  print_variables v_selected_disks
+}
+
+function ask_swap_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local swap_size_invalid_message=
+
+  while [[ ! $v_swap_size =~ ^[0-9]+$ ]]; do
+    v_swap_size=$(dialog --inputbox "${swap_size_invalid_message}Enter the swap size in GiB (0 for no swap):" 30 100 2 3>&1 1>&2 2>&3)
+
+    swap_size_invalid_message="Invalid swap size! "
+  done
+
+  print_variables v_swap_size
+}
+
+function ask_free_tail_space {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local tail_space_invalid_message=
+
+  while [[ ! $v_free_tail_space =~ ^[0-9]+$ ]]; do
+    v_free_tail_space=$(dialog --inputbox "${tail_space_invalid_message}Enter the space to leave at the end of each disk (0 for none):" 30 100 0 3>&1 1>&2 2>&3)
+
+    tail_space_invalid_message="Invalid size! "
+  done
+
+  print_variables v_free_tail_space
+}
+
+function ask_zfs_arc_max_size {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local zfs_arc_max_invalid_message=
+
+  while [[ ! $v_zfs_arc_max_mb =~ ^[0-9]+$ ]]; do
+    v_zfs_arc_max_mb=$(dialog --inputbox "${zfs_arc_max_invalid_message}Enter ZFS ARC cache max size in Mb (minimum 64Mb, enter 0 for ZFS default value, the default will take up to 50% of memory):" 30 100 "$c_default_zfs_arc_max_mb" 3>&1 1>&2 2>&3)
+
+    zfs_arc_max_invalid_message="Invalid size! "
+  done
+
+  print_variables v_zfs_arc_max_mb
+}
+
+
+function ask_pool_names {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local bpool_name_invalid_message=
+
+  while [[ ! $v_bpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_bpool_name=$(dialog --inputbox "${bpool_name_invalid_message}Insert the name for the boot pool" 30 100 bpool 3>&1 1>&2 2>&3)
+
+    bpool_name_invalid_message="Invalid pool name! "
+  done
+  local rpool_name_invalid_message=
+
+  while [[ ! $v_rpool_name =~ ^[a-z][a-zA-Z_:.-]+$ ]]; do
+    v_rpool_name=$(dialog --inputbox "${rpool_name_invalid_message}Insert the name for the root pool" 30 100 rpool 3>&1 1>&2 2>&3)
+
+    rpool_name_invalid_message="Invalid pool name! "
+  done
+
+  print_variables v_bpool_name v_rpool_name
+}
+
+function ask_pool_tweaks {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  v_bpool_tweaks=$(dialog --inputbox "Insert the tweaks for the boot pool" 30 100 -- "$c_default_bpool_tweaks" 3>&1 1>&2 2>&3)
+  v_rpool_tweaks=$(dialog --inputbox "Insert the tweaks for the root pool" 30 100 -- "$c_default_rpool_tweaks" 3>&1 1>&2 2>&3)
+
+  print_variables v_bpool_tweaks v_rpool_tweaks
+}
+
+
+function ask_root_password {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  set +x
+  local password_invalid_message=
+  local password_repeat=-
+
+  while [[ "$v_root_password" != "$password_repeat" || "$v_root_password" == "" ]]; do
+    v_root_password=$(dialog --passwordbox "${password_invalid_message}Please enter the root account password (can't be empty):" 30 100 3>&1 1>&2 2>&3)
+    password_repeat=$(dialog --passwordbox "Please repeat the password:" 30 100 3>&1 1>&2 2>&3)
+
+    password_invalid_message="Passphrase empty, or not matching! "
+  done
+  set -x
+}
+
+function ask_encryption {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to encrypt the root pool?' 30 100; then
+    v_encrypt_rpool=1
+  fi
+  set +x
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    local passphrase_invalid_message=
+    local passphrase_repeat=-
+    while [[ "$v_passphrase" != "$passphrase_repeat" || ${#v_passphrase} -lt 8 ]]; do
+      v_passphrase=$(dialog --passwordbox "${passphrase_invalid_message}Please enter the passphrase for the root pool (8 chars min.):" 30 100 3>&1 1>&2 2>&3)
+      passphrase_repeat=$(dialog --passwordbox "Please repeat the passphrase:" 30 100 3>&1 1>&2 2>&3)
+
+      passphrase_invalid_message="Passphrase too short, or not matching! "
+    done
+  fi
+  set -x
+}
+
+function ask_zfs_experimental {
+  print_step_info_header
+
+  if dialog --defaultno --yesno 'Do you want to use experimental zfs module build?' 30 100; then
+    v_zfs_experimental=1
+  fi
+}
+
+function ask_hostname {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  local hostname_invalid_message=
+
+  while [[ ! $v_hostname =~ ^[a-z][a-zA-Z0-9_:.-]+$ ]]; do
+    v_hostname=$(dialog --inputbox "${hostname_invalid_message}Set the host name" 30 100 "$c_default_hostname" 3>&1 1>&2 2>&3)
+
+    hostname_invalid_message="Invalid host name! "
+  done
+
+  print_variables v_hostname
+}
+
+function determine_kernel_variant {
+  if dmidecode | grep -q vServer; then
+    v_kernel_variant="-virtual"
+  else
+    v_kernel_variant="-generic"
+  fi
+}
+
+function chroot_execute {
+  chroot $c_zfs_mount_dir bash -c "DEBIAN_FRONTEND=noninteractive $1"
+}
+
+function unmount_and_export_fs {
+  # shellcheck disable=SC2119
+  print_step_info_header
+
+  for virtual_fs_dir in dev sys proc; do
+    umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+  done
+
+  local max_unmount_wait=5
+  echo -n "Waiting for virtual filesystems to unmount "
+
+  SECONDS=0
+
+  for virtual_fs_dir in dev sys proc; do
+    while mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir" && [[ $SECONDS -lt $max_unmount_wait ]]; do
+      sleep 0.5
+      echo -n .
+    done
+  done
+
+  echo
+
+  for virtual_fs_dir in dev sys proc; do
+    if mountpoint -q "$c_zfs_mount_dir/$virtual_fs_dir"; then
+      echo "Re-issuing umount for $c_zfs_mount_dir/$virtual_fs_dir"
+      umount --recursive --force --lazy "$c_zfs_mount_dir/$virtual_fs_dir"
+    fi
+  done
+
+  SECONDS=0
+  zpools_exported=99
+  echo "===========exporting zfs pools============="
+  set +e
+  while (( zpools_exported == 99 )) && (( SECONDS++ <= 60 )); do
+    
+    if zpool export -a 2> /dev/null; then
+      zpools_exported=1
+      echo "all zfs pools were succesfully exported"
+      break;
+    else
+      sleep 1
+     fi
+  done
+  set -e
+  if (( zpools_exported != 1 )); then
+    echo "failed to export zfs pools"
+    exit 1
+  fi
+}
+
+#################### MAIN ################################
+export LC_ALL=en_US.UTF-8
+export NCURSES_NO_UTF8_ACS=1
+
+check_prerequisites
+
+display_intro_banner
+
+activate_debug
+
+find_suitable_disks
+
+select_disks
+
+ask_swap_size
+
+ask_free_tail_space
+
+ask_pool_names
+
+ask_pool_tweaks
+
+ask_encryption
+
+ask_zfs_arc_max_size
+
+ask_zfs_experimental
+
+ask_root_password
+
+ask_hostname
+
+determine_kernel_variant
+
+clear
+
+echo "===========remove unused kernels in rescue system========="
+for kver in $(find /lib/modules/* -maxdepth 0 -type d | grep -v "$(uname -r)" | cut -s -d "/" -f 4); do
+  apt purge --yes "linux-headers-$kver"
+  apt purge --yes "linux-image-$kver"
+done
+
+echo "======= installing zfs on rescue system =========="
+  echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections  
+#  echo "y" | zfs
+# linux-headers-generic linux-image-generic
+  apt install --yes software-properties-common dpkg-dev dkms
+  rm -f "$(which zfs)"
+  rm -f "$(which zpool)"
+  echo -e "deb http://deb.debian.org/debian/ testing main contrib non-free\ndeb http://deb.debian.org/debian/ testing main contrib non-free\n" >/etc/apt/sources.list.d/bookworm-testing.list
+  echo -e "Package: src:zfs-linux\nPin: release n=testing\nPin-Priority: 990\n" > /etc/apt/preferences.d/90_zfs
+  apt update  
+  apt install -t testing --yes zfs-dkms zfsutils-linux
+  rm /etc/apt/sources.list.d/bookworm-testing.list
+  rm /etc/apt/preferences.d/90_zfs
+  apt update
+  export PATH=$PATH:/usr/sbin
+  zfs --version
+
+echo "======= partitioning the disk =========="
+
+  if [[ $v_free_tail_space -eq 0 ]]; then
+    tail_space_parameter=0
+  else
+    tail_space_parameter="-${v_free_tail_space}G"
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    wipefs --all --force "$selected_disk"
+    sgdisk -a1 -n1:24K:+1000K            -t1:EF02 "$selected_disk"
+    sgdisk -n2:0:+2G                   -t2:BF01 "$selected_disk" # Boot pool
+    sgdisk -n3:0:"$tail_space_parameter" -t3:BF01 "$selected_disk" # Root pool
+  done
+
+  udevadm settle
+
+echo "======= create zfs pools and datasets =========="
+
+  encryption_options=()
+  rpool_disks_partitions=()
+  bpool_disks_partitions=()
+
+  if [[ $v_encrypt_rpool == "1" ]]; then
+    encryption_options=(-O "encryption=aes-256-gcm" -O "keylocation=prompt" -O "keyformat=passphrase")
+  fi
+
+  for selected_disk in "${v_selected_disks[@]}"; do
+    rpool_disks_partitions+=("${selected_disk}-part3")
+    bpool_disks_partitions+=("${selected_disk}-part2")
+  done
+
+  if [[ ${#v_selected_disks[@]} -gt 1 ]]; then
+    pools_mirror_option=mirror
+  else
+    pools_mirror_option=
+  fi
+
+# shellcheck disable=SC2086
+zpool create \
+  $v_bpool_tweaks -O canmount=off -O devices=off \
+  -o cachefile=/etc/zpool.cache \
+  -O mountpoint=/boot -R $c_zfs_mount_dir -f \
+  $v_bpool_name $pools_mirror_option "${bpool_disks_partitions[@]}"
+
+# shellcheck disable=SC2086
+echo -n "$v_passphrase" | zpool create \
+  $v_rpool_tweaks \
+  -o cachefile=/etc/zpool.cache \
+  "${encryption_options[@]}" \
+  -O mountpoint=/ -R $c_zfs_mount_dir -f \
+  $v_rpool_name $pools_mirror_option "${rpool_disks_partitions[@]}"
+
+zfs create -o canmount=off -o mountpoint=none "$v_rpool_name/ROOT"
+zfs create -o canmount=off -o mountpoint=none "$v_bpool_name/BOOT"
+
+zfs create -o canmount=noauto -o mountpoint=/ "$v_rpool_name/ROOT/ubuntu"
+zfs mount "$v_rpool_name/ROOT/ubuntu"
+
+zfs create -o canmount=noauto -o mountpoint=/boot "$v_bpool_name/BOOT/ubuntu"
+zfs mount "$v_bpool_name/BOOT/ubuntu"
+
+zfs create                                 "$v_rpool_name/home"
+#zfs create -o mountpoint=/root             "$v_rpool_name/home/root"
+zfs create -o canmount=off                 "$v_rpool_name/var"
+zfs create                                 "$v_rpool_name/var/log"
+zfs create                                 "$v_rpool_name/var/spool"
+
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/cache"
+zfs create -o com.sun:auto-snapshot=false  "$v_rpool_name/var/tmp"
+chmod 1777 "$c_zfs_mount_dir/var/tmp"
+
+zfs create                                 "$v_rpool_name/srv"
+
+zfs create -o canmount=off                 "$v_rpool_name/usr"
+zfs create                                 "$v_rpool_name/usr/local"
+
+zfs create                                 "$v_rpool_name/var/mail"
+
+zfs create -o com.sun:auto-snapshot=false -o canmount=on -o mountpoint=/tmp "$v_rpool_name/tmp"
+chmod 1777 "$c_zfs_mount_dir/tmp"
+
+if [[ $v_swap_size -gt 0 ]]; then
+  zfs create \
+    -V "${v_swap_size}G" -b "$(getconf PAGESIZE)" \
+    -o compression=zle -o logbias=throughput -o sync=always -o primarycache=metadata -o secondarycache=none -o com.sun:auto-snapshot=false \
+    "$v_rpool_name/swap"
+
+  udevadm settle
+
+  mkswap -f "/dev/zvol/$v_rpool_name/swap"
+fi
+
+echo "======= setting up initial system packages =========="
+debootstrap --arch=amd64 jammy "$c_zfs_mount_dir" "$c_deb_packages_repo"
+
+zfs set devices=off "$v_rpool_name"
+
+echo "======= setting up the network =========="
+
+echo "$v_hostname" > $c_zfs_mount_dir/etc/hostname
+
+cat > "$c_zfs_mount_dir/etc/hosts" <<CONF
+127.0.1.1 ${v_hostname}
+127.0.0.1 localhost
+
+# The following lines are desirable for IPv6 capable hosts
+::1 ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+CONF
+
+ip6addr_prefix=$(ip -6 a s | grep -E "inet6.+global" | sed -nE 's/.+inet6\s(([0-9a-z]{1,4}:){4,4}).+/\1/p' | head -n 1)
+
+cat <<CONF > /mnt/etc/systemd/network/10-eth0.network
+[Match]
+Name=eth0
+
+[Network]
+DHCP=ipv4
+Address=${ip6addr_prefix}:1/64
+Gateway=fe80::1
+CONF
+
+chroot_execute "systemctl enable systemd-networkd.service"
+chroot_execute "systemctl enable systemd-resolved.service"
+
+
+mkdir -p "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/"
+cat > "$c_zfs_mount_dir/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg" <<CONF
+network:
+  config: disabled
+CONF
+
+rm -rf $c_zfs_mount_dir/etc/network/interfaces.d/50-cloud-init.cfg
+
+echo "======= preparing the jail for chroot =========="
+for virtual_fs_dir in proc sys dev; do
+  mount --rbind "/$virtual_fs_dir" "$c_zfs_mount_dir/$virtual_fs_dir"
+done
+
+echo "======= setting apt repos =========="
+cat > "$c_zfs_mount_dir/etc/apt/sources.list" <<CONF
+deb [arch=i386,amd64] $c_deb_packages_repo jammy main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo jammy-updates main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo jammy-backports main restricted
+deb [arch=i386,amd64] $c_deb_packages_repo jammy universe
+deb [arch=i386,amd64] $c_deb_security_repo jammy-security main restricted
+CONF
+
+chroot_execute "apt update"
+
+echo "======= setting locale, console and language =========="
+chroot_execute "apt --yes --fix-broken install"
+chroot_execute "apt install --yes -qq locales debconf-i18n apt-utils keyboard-configuration console-setup"
+sed -i 's/# en_US.UTF-8/en_US.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# fr_FR.UTF-8/fr_FR.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_AT.UTF-8/de_AT.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+sed -i 's/# de_DE.UTF-8/de_DE.UTF-8/' "$c_zfs_mount_dir/etc/locale.gen"
+
+chroot_execute 'cat <<CONF | debconf-set-selections
+locales locales/default_environment_locale      select  en_US.UTF-8
+keyboard-configuration  keyboard-configuration/store_defaults_in_debconf_db     boolean true
+keyboard-configuration  keyboard-configuration/variant  select  German
+keyboard-configuration  keyboard-configuration/unsupported_layout       boolean true
+keyboard-configuration  keyboard-configuration/modelcode        string  pc105
+keyboard-configuration  keyboard-configuration/unsupported_config_layout        boolean true
+keyboard-configuration  keyboard-configuration/layout   select  German
+keyboard-configuration  keyboard-configuration/layoutcode       string  de
+keyboard-configuration  keyboard-configuration/optionscode      string
+keyboard-configuration  keyboard-configuration/toggle   select  No toggling
+keyboard-configuration  keyboard-configuration/xkb-keymap       select  de
+keyboard-configuration  keyboard-configuration/switch   select  No temporary switch
+keyboard-configuration  keyboard-configuration/unsupported_config_options       boolean true
+keyboard-configuration  keyboard-configuration/ctrl_alt_bksp    boolean false
+keyboard-configuration  keyboard-configuration/variantcode      string
+keyboard-configuration  keyboard-configuration/model    select  Generic 105-key PC (intl.)
+keyboard-configuration  keyboard-configuration/altgr    select  The default for the keyboard layout
+keyboard-configuration  keyboard-configuration/compose  select  No compose key
+keyboard-configuration  keyboard-configuration/unsupported_options      boolean true
+console-setup   console-setup/fontsize-fb47     select  8x16
+console-setup   console-setup/store_defaults_in_debconf_db      boolean true
+console-setup   console-setup/codeset47 select  # Latin1 and Latin5 - western Europe and Turkic languages
+console-setup   console-setup/fontface47        select  Fixed
+console-setup   console-setup/fontsize  string  8x16
+console-setup   console-setup/charmap47 select  UTF-8
+console-setup   console-setup/fontsize-text47   select  8x16
+console-setup   console-setup/codesetcode       string  Lat15
+tzdata tzdata/Areas select Europe
+tzdata tzdata/Zones/Europe select Vienna
+grub-pc grub-pc/install_devices_empty   boolean true
+CONF'
+
+chroot_execute "dpkg-reconfigure locales -f noninteractive"
+echo -e "LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8\n" >> "$c_zfs_mount_dir/etc/environment"
+chroot_execute "dpkg-reconfigure keyboard-configuration -f noninteractive"
+chroot_execute "dpkg-reconfigure console-setup -f noninteractive"
+chroot_execute "setupcon"
+
+chroot_execute "rm -f /etc/localtime /etc/timezone"
+chroot_execute "dpkg-reconfigure tzdata -f noninteractive "
+
+echo "======= installing latest kernel============="
+chroot_execute "apt install --yes linux-headers${v_kernel_variant} linux-image${v_kernel_variant}"
+if [[ $v_kernel_variant == "-virtual" ]]; then
+  # linux-image-extra is only available for virtual hosts
+  chroot_execute "apt install --yes linux-image-extra-virtual"
+fi
+
+
+echo "======= installing aux packages =========="
+chroot_execute "apt install --yes man-db wget curl software-properties-common nano htop gnupg"
+chroot_execute "systemctl disable thermald"
+
+echo "======= installing zfs packages =========="
+chroot_execute 'echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections'
+
+if [[ $v_zfs_experimental == "1" ]]; then
+  chroot_execute "wget -O - https://terem42.github.io/zfs-debian/apt_pub.gpg | apt-key add -"
+  chroot_execute "add-apt-repository 'deb https://terem42.github.io/zfs-debian/public zfs-debian-experimental main'"
+  chroot_execute "apt update"
+  chroot_execute "apt install -t zfs-debian-experimental --yes zfs-initramfs zfs-dkms zfsutils-linux"
+else
+  chroot_execute "add-apt-repository --yes ppa:jonathonf/zfs"
+  chroot_execute "apt install --yes zfs-initramfs zfs-dkms zfsutils-linux"
+fi
+chroot_execute 'cat << DKMS > /etc/dkms/zfs.conf
+# override for /usr/src/zfs-*/dkms.conf:
+# always rebuild initrd when zfs module has been changed
+# (either by a ZFS update or a new kernel version)
+REMAKE_INITRD="yes"
+DKMS'
+
+echo "======= installing OpenSSH and network tooling =========="
+chroot_execute "apt install --yes openssh-server net-tools"
+
+echo "======= setup OpenSSH  =========="
+mkdir -p "$c_zfs_mount_dir/root/.ssh/"
+cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/root/.ssh/authorized_keys"
+sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$c_zfs_mount_dir/etc/ssh/sshd_config"
+chroot_execute "rm /etc/ssh/ssh_host_*"
+chroot_execute "dpkg-reconfigure openssh-server -f noninteractive"
+
+echo "======= set root password =========="
+chroot_execute "echo root:$(printf "%q" "$v_root_password") | chpasswd"
+
+echo "======= setting up zfs cache =========="
+cp /etc/zpool.cache /mnt/etc/zfs/zpool.cache
+
+echo "========setting up zfs module parameters========"
+chroot_execute "echo options zfs zfs_arc_max=$((v_zfs_arc_max_mb * 1024 * 1024)) >> /etc/modprobe.d/zfs.conf"
+
+echo "======= setting up grub =========="
+chroot_execute "echo 'grub-pc grub-pc/install_devices_empty   boolean true' | debconf-set-selections"
+chroot_execute "apt install --yes grub-pc"
+for disk in ${v_selected_disks[@]}; do
+  chroot_execute "grub-install $disk"
+done
+
+chroot_execute "sed -i 's/#GRUB_TERMINAL=console/GRUB_TERMINAL=console/g' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT=\"net.ifnames=0\"|' /etc/default/grub"
+chroot_execute "sed -i 's|GRUB_CMDLINE_LINUX=\"\"|GRUB_CMDLINE_LINUX=\"root=ZFS=$v_rpool_name/ROOT/ubuntu\"|g' /etc/default/grub"
+
+chroot_execute "sed -i 's/quiet//g' /etc/default/grub"
+chroot_execute "sed -i 's/splash//g' /etc/default/grub"
+chroot_execute "echo 'GRUB_DISABLE_OS_PROBER=true'   >> /etc/default/grub"
+
+for ((i = 1; i < ${#v_selected_disks[@]}; i++)); do
+  dd if="${v_selected_disks[0]}-part1" of="${v_selected_disks[i]}-part1"
+done
+
+if [[ $v_encrypt_rpool == "1" ]]; then
+  echo "=========set up dropbear=============="
+  chroot_execute "apt install --yes dropbear-initramfs"
+  
+  mkdir -p "$c_zfs_mount_dir/etc/dropbear/initramfs"
+  cp /root/.ssh/authorized_keys "$c_zfs_mount_dir/etc/dropbear/initramfs/authorized_keys"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_rsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_rsa_key_temp /etc/dropbear/initramfs/dropbear_rsa_host_key"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_rsa_key_temp"
+
+  cp "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key" "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "ssh-keygen -p -i -m pem -N '' -f /etc/ssh/ssh_host_ecdsa_key_temp"
+  chroot_execute "/usr/lib/dropbear/dropbearconvert openssh dropbear /etc/ssh/ssh_host_ecdsa_key_temp /etc/dropbear/initramfs/dropbear_ecdsa_host_key"
+  chroot_execute "rm -rf /etc/ssh/ssh_host_ecdsa_key_temp"
+  rm -rf "$c_zfs_mount_dir/etc/ssh/ssh_host_ecdsa_key_temp"
+
+  rm -rf "$c_zfs_mount_dir/etc/dropbear/initramfs/dropbear_dss_host_key"
+fi
+
+echo "============setup root prompt============"
+cat > "$c_zfs_mount_dir/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+
+echo "========running packages upgrade==========="
+chroot_execute "apt upgrade --yes"
+chroot_execute "apt purge cryptsetup* --yes"
+
+echo "===========add static route to initramfs via hook to add default routes due to Ubuntu initramfs DHCP bug ========="
+mkdir -p "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount"
+cat > "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route" <<'CONF'
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+    echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+
+. /scripts/functions
+# Begin real processing below this line
+
+configure_networking
+
+ip route add 172.31.1.1/255.255.255.255 dev ens3
+ip route add default via 172.31.1.1 dev ens3
+CONF
+
+chmod 755 "$c_zfs_mount_dir/usr/share/initramfs-tools/scripts/init-premount/static-route"
+
+echo "======= update initramfs =========="
+chroot_execute "update-initramfs -u -k all"
+
+echo "======= update grub =========="
+chroot_execute "update-grub"
+
+echo "======= setting up zed =========="
+
+chroot_execute "zfs set canmount=noauto $v_rpool_name"
+
+echo "======= setting mountpoints =========="
+chroot_execute "zfs set mountpoint=legacy $v_bpool_name/BOOT/ubuntu"
+chroot_execute "echo $v_bpool_name/BOOT/ubuntu /boot zfs nodev,relatime,x-systemd.requires=zfs-mount.service,x-systemd.device-timeout=10 0 0 > /etc/fstab"
+
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/log"
+chroot_execute "echo $v_rpool_name/var/log /var/log zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/spool"
+chroot_execute "echo $v_rpool_name/var/spool /var/spool zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/var/tmp"
+chroot_execute "echo $v_rpool_name/var/tmp /var/tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+chroot_execute "zfs set mountpoint=legacy $v_rpool_name/tmp"
+chroot_execute "echo $v_rpool_name/tmp /tmp zfs nodev,relatime 0 0 >> /etc/fstab"
+
+echo "========= add swap, if defined"
+if [[ $v_swap_size -gt 0 ]]; then
+  chroot_execute "echo /dev/zvol/$v_rpool_name/swap none swap discard 0 0 >> /etc/fstab"
+fi
+
+chroot_execute "echo RESUME=none > /etc/initramfs-tools/conf.d/resume"
+
+echo "======= unmounting filesystems and zfs pools =========="
+unmount_and_export_fs
+
+echo "======== setup complete, rebooting ==============="
+reboot

hetzner-ubuntu24-zfs-setup.sh

@@ -0,0 +1,973 @@
+#!/bin/bash
+
+: <<'end_header_info'
+(c) Andrey Prokopenko job@terem.fr
+fully automatic script to install Ubuntu 24 with ZFS root on Hetzner VPS
+WARNING: all data on the disk will be destroyed
+How to use: add SSH key to the rescue console, then press "mount rescue and power cycle" button
+Next, connect via SSH to console, and run the script
+Answer script questions about desired hostname and ZFS ARC cache size
+To cope with network failures its higly recommended to run the script inside screen console
+screen -dmS zfs
+screen -r zfs
+To detach from screen console, hit Ctrl-d then a
+end_header_info
+
+set -euo pipefail
+
+# ---- Configuration ----
+# These will be set by user input
+SYSTEM_HOSTNAME=""
+ROOT_PASSWORD=""
+ZFS_POOL=""
+UBUNTU_CODENAME="noble"   # Ubuntu 24.04
+TARGET="/mnt/ubuntu"
+
+ZBM_BIOS_URL="https://github.com/zbm-dev/zfsbootmenu/releases/download/v3.0.1/zfsbootmenu-release-x86_64-v3.0.1-linux6.1.tar.gz"
+ZBM_EFI_URL="https://github.com/zbm-dev/zfsbootmenu/releases/download/v3.0.1/zfsbootmenu-release-x86_64-v3.0.1-linux6.1.EFI"
+
+MAIN_BOOT="/main_boot"
+
+# Hetzner mirrors
+MIRROR_SITE="https://mirror.hetzner.com"
+MIRROR_MAIN="deb ${MIRROR_SITE}/ubuntu/packages ${UBUNTU_CODENAME} main restricted universe multiverse"
+MIRROR_UPDATES="deb ${MIRROR_SITE}/ubuntu/packages ${UBUNTU_CODENAME}-updates main restricted universe multiverse"
+MIRROR_BACKPORTS="deb ${MIRROR_SITE}/ubuntu/packages ${UBUNTU_CODENAME}-backports main restricted universe multiverse"
+MIRROR_SECURITY="deb ${MIRROR_SITE}/ubuntu/security ${UBUNTU_CODENAME}-security main restricted universe multiverse"
+
+# Global variables
+INSTALL_DISK=""
+EFI_MODE=false
+BOOT_LABEL=""
+BOOT_TYPE=""
+BOOT_PART=""
+ZFS_PART=""
+
+# ---- User Input Functions ----
+function setup_whiptail_colors {
+    # Green text on black background - classic terminal theme
+    export NEWT_COLORS='
+    root=green,black
+    window=green,black
+    shadow=green,black
+    border=green,black
+    title=green,black
+    textbox=green,black
+    button=black,green
+    listbox=green,black
+    actlistbox=black,green
+    actsellistbox=black,green
+    checkbox=green,black
+    actcheckbox=black,green
+    entry=green,black
+    label=green,black
+    '
+}
+
+function check_whiptail {
+    if ! command -v whiptail &> /dev/null; then
+        echo "Installing whiptail..."
+        apt update
+        apt install -y whiptail
+    fi
+    setup_whiptail_colors
+}
+
+
+function get_hostname {
+    while true; do
+        SYSTEM_HOSTNAME=$(whiptail \
+            --title "System Hostname" \
+            --inputbox "Enter the hostname for the new system:" \
+            10 60 "zfs-ubuntu" \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            whiptail --title "Cancelled" --msgbox "Installation cancelled by user." 10 50
+            exit 1
+        fi
+        
+        # Validate hostname
+        if [[ "$SYSTEM_HOSTNAME" =~ ^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$ ]] && [[ ${#SYSTEM_HOSTNAME} -le 63 ]]; then
+            break
+        else
+            whiptail \
+                --title "Invalid Hostname" \
+                --msgbox "Invalid hostname. Please use only letters, numbers, and hyphens. Must start and end with alphanumeric character. Maximum 63 characters." \
+                12 60
+        fi
+    done
+}
+
+function get_zfs_pool_name {
+    while true; do
+        ZFS_POOL=$(whiptail \
+            --title "ZFS Pool Name" \
+            --inputbox "Enter the name for the ZFS pool:" \
+            10 60 "rpool" \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            whiptail --title "Cancelled" --msgbox "Installation cancelled by user." 10 50
+            exit 1
+        fi
+        
+        # Validate ZFS pool name
+        if [[ "$ZFS_POOL" =~ ^[a-zA-Z][a-zA-Z0-9_-]*$ ]] && [[ ${#ZFS_POOL} -le 255 ]]; then
+            break
+        else
+            whiptail \
+                --title "Invalid Pool Name" \
+                --msgbox "Invalid ZFS pool name. Must start with a letter and contain only letters, numbers, hyphens, and underscores. Maximum 255 characters." \
+                12 60
+        fi
+    done
+}
+
+function get_root_password {
+    while true; do
+        # Get first password input
+        local password1
+        local password2
+        
+        password1=$(whiptail \
+            --title "Root Password" \
+            --passwordbox "Enter root password (input hidden):" \
+            10 60 \
+            3>&1 1>&2 2>&3)
+        
+        local exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            whiptail --title "Cancelled" --msgbox "Installation cancelled by user." 10 50
+            exit 1
+        fi
+        
+        # Get password confirmation
+        password2=$(whiptail \
+            --title "Confirm Root Password" \
+            --passwordbox "Confirm root password (input hidden):" \
+            10 60 \
+            3>&1 1>&2 2>&3)
+        
+        exit_status=$?
+        if [ $exit_status -ne 0 ]; then
+            whiptail --title "Cancelled" --msgbox "Installation cancelled by user." 10 50
+            exit 1
+        fi
+        
+        # Check if passwords match
+        if [ "$password1" = "$password2" ]; then
+            if [ -n "$password1" ]; then
+                ROOT_PASSWORD="$password1"
+                break
+            else
+                whiptail \
+                    --title "Empty Password" \
+                    --msgbox "Password cannot be empty. Please enter a password." \
+                    10 50
+            fi
+        else
+            whiptail \
+                --title "Password Mismatch" \
+                --msgbox "Passwords do not match. Please try again." \
+                10 50
+        fi
+    done
+}
+
+function show_summary_and_confirm {
+    local summary="Please review the installation settings:
+
+Hostname: $SYSTEM_HOSTNAME
+ZFS Pool: $ZFS_POOL
+Ubuntu Version: $UBUNTU_CODENAME (24.04)
+Target: $TARGET
+Boot Mode: $([ "$EFI_MODE" = true ] && echo "EFI" || echo "BIOS")
+Install Disk: $INSTALL_DISK
+
+*** WARNING: This will DESTROY ALL DATA on $INSTALL_DISK! ***
+
+Do you want to continue with the installation?"
+    
+    if whiptail \
+        --title " Installation Summary " \
+        --yesno "$summary" \
+        18 60; then
+        # User confirmed - just continue silently
+        echo "User confirmed installation. Starting now..."
+    else
+        echo "Installation cancelled by user."
+        exit 1
+    fi
+}
+
+function get_user_input {
+    echo "======= Gathering Installation Parameters =========="
+    check_whiptail
+    
+    # Show welcome message
+    whiptail \
+        --title "ZFS Ubuntu Installer" \
+        --msgbox "Welcome to the ZFS Ubuntu Installer for Hetzner Cloud.\n\nThis script will install Ubuntu 24.04 with ZFS root on your server." \
+        12 60
+    
+    # Get user inputs
+    get_hostname
+    get_zfs_pool_name
+    get_root_password
+}
+
+# ---- System Detection Functions ----
+function detect_efi {
+    echo "======= Detecting EFI support =========="
+    
+    if [ -d /sys/firmware/efi ]; then
+        echo "✓ EFI firmware detected"
+        EFI_MODE=true
+        BOOT_LABEL="EFI"
+        BOOT_TYPE="ef00"
+    else
+        echo "✓ Legacy BIOS mode detected"
+        EFI_MODE=false
+        BOOT_LABEL="boot"
+        BOOT_TYPE="8300"
+    fi
+}
+
+function find_install_disk {
+    echo "======= Finding install disk =========="
+    
+    local candidate_disks=()
+    
+    # Use lsblk to find all unmounted, writable disks
+    while IFS= read -r disk; do
+        [[ -n "$disk" ]] && candidate_disks+=("$disk")
+    done < <(lsblk -npo NAME,TYPE,RO,MOUNTPOINT | awk '
+        $2 == "disk" && $3 == "0" && $4 == "" {print $1}
+    ')
+    
+    if [[ ${#candidate_disks[@]} -eq 0 ]]; then
+        echo "No suitable installation disks found" >&2
+        echo "Looking for: unmounted, writable disks without partitions in use" >&2
+        exit 1
+    fi
+    
+    INSTALL_DISK="${candidate_disks[0]}"
+    echo "Using installation disk: $INSTALL_DISK"
+    
+    # Show all available disks for verification
+    echo "All available disks:"
+    lsblk -o NAME,SIZE,TYPE,MOUNTPOINT,RO | grep -v loop
+}
+
+# ---- Rescue System Preparation Functions ----
+function remove_unused_kernels {
+    echo "=========== Removing unused kernels in rescue system =========="
+    for kver in $(find /lib/modules/* -maxdepth 0 -type d \
+                    | grep -v "$(uname -r)" \
+                    | cut -s -d "/" -f 4); do
+
+        for pkg in "linux-headers-$kver" "linux-image-$kver"; do
+            if dpkg -l "$pkg" 2>/dev/null | grep -q '^ii'; then
+                echo "Purging $pkg ..."
+                apt purge --yes "$pkg"
+            else
+                echo "Package $pkg not installed, skipping."
+            fi
+        done
+    done
+}
+
+function install_zfs_on_rescue_system {
+    echo "======= Installing ZFS on rescue system =========="
+    echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
+    # Enable Hetzner bookworm-backports
+    sed -i 's/^# deb http:\/\/mirror.hetzner.com\/debian\/packages bookworm-backports/deb http:\/\/mirror.hetzner.com\/debian\/packages bookworm-backports/' /etc/apt/sources.list
+    apt update
+    apt -t bookworm-backports install -y zfsutils-linux
+}
+
+# ---- Disk Partitioning Functions ----
+function partition_disk {
+    echo "======= Partitioning disk =========="
+    sgdisk -Z "$INSTALL_DISK"  
+    
+    if [ "$EFI_MODE" = true ]; then
+        echo "Creating EFI partition layout"
+        # EFI System Partition (ESP) - 64MB is plenty for ZFSBootMenu
+        sgdisk -n1:1M:+128M -t1:ef00 -c1:"EFI" "$INSTALL_DISK"
+        # ZFS partition
+        sgdisk -n2:0:0   -t2:bf00 -c2:"zfs"  "$INSTALL_DISK"
+    else
+        echo "Creating BIOS partition layout"
+        # /boot partition - 64MB is also sufficient for BIOS ZFSBootMenu
+        sgdisk -n1:1M:+128M -t1:8300 -c1:"boot" "$INSTALL_DISK"
+        # ZFS partition
+        sgdisk -n2:0:0   -t2:bf00 -c2:"zfs"  "$INSTALL_DISK"
+        # Set legacy BIOS bootable flag
+        sgdisk -A 1:set:2 "$INSTALL_DISK"
+    fi
+    
+    partprobe "$INSTALL_DISK" || true
+    udevadm settle
+    
+    # Set partition variables based on mode
+    if [ "$EFI_MODE" = true ]; then
+        BOOT_PART="$(blkid -t PARTLABEL='EFI' -o device)"
+        ZFS_PART="$(blkid -t PARTLABEL='zfs' -o device)"
+        # Format ESP as FAT32
+        mkfs.fat -F 32 -n EFI "$BOOT_PART"
+    else
+        BOOT_PART="$(blkid -t PARTLABEL='boot' -o device)"
+        ZFS_PART="$(blkid -t PARTLABEL='zfs' -o device)"
+        mkfs.ext4 -F -L boot "$BOOT_PART"
+    fi
+}
+
+# ---- ZFS Pool and Dataset Functions ----
+function create_zfs_pool {
+    echo "======= Creating ZFS pool =========="
+    # Clean up any existing ZFS binaries in PATH
+    rm -f "$(which zfs)" 2>/dev/null || true
+    rm -f "$(which zpool)" 2>/dev/null || true
+    
+    export PATH=/usr/sbin:$PATH
+    modprobe zfs
+    
+    zpool create -f -o ashift=12 \
+    -o cachefile="/etc/zfs/zpool.cache" \
+    -O compression=lz4 \
+    -O acltype=posixacl \
+    -O xattr=sa \
+    -O mountpoint=none \
+    "$ZFS_POOL" "$ZFS_PART"
+
+    zfs create -o mountpoint=none   "$ZFS_POOL/ROOT"
+    zfs create -o mountpoint=legacy "$ZFS_POOL/ROOT/ubuntu"
+
+    echo "======= Assigning $ZFS_POOL/ROOT/ubuntu dataset as bootable =========="
+    zpool set bootfs="$ZFS_POOL/ROOT/ubuntu" "$ZFS_POOL"
+    zpool set cachefile="/etc/zfs/zpool.cache" "$ZFS_POOL"
+}
+
+function create_additional_zfs_datasets {
+    echo "======= Creating additional ZFS datasets with TEMPORARY mountpoints =========="
+    
+    # Ensure parent datasets are created first
+    zfs create -o mountpoint=none "$ZFS_POOL/ROOT/ubuntu/var"
+    zfs create -o mountpoint=none "$ZFS_POOL/ROOT/ubuntu/var/cache"
+    
+    # Create leaf datasets with temporary mountpoints under $TARGET
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/tmp" "$ZFS_POOL/ROOT/ubuntu/tmp"
+    zfs set devices=off "$ZFS_POOL/ROOT/ubuntu/tmp"
+    
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/var/tmp" "$ZFS_POOL/ROOT/ubuntu/var/tmp"
+    zfs set devices=off "$ZFS_POOL/ROOT/ubuntu/var/tmp"
+    
+    zfs create -o mountpoint="$TARGET/var/log" "$ZFS_POOL/ROOT/ubuntu/var/log"    
+    zfs set atime=off "$ZFS_POOL/ROOT/ubuntu/var/log"
+    
+    zfs create -o com.sun:auto-snapshot=false -o mountpoint="$TARGET/var/cache/apt" "$ZFS_POOL/ROOT/ubuntu/var/cache/apt"    
+    zfs set atime=off "$ZFS_POOL/ROOT/ubuntu/var/cache/apt"
+    
+    # Create home dataset separately
+    zfs create -o mountpoint="$TARGET/home" "$ZFS_POOL/home"
+    
+    # Mount all datasets
+    zfs mount -a
+    
+    # Set permissions on the actual ZFS datasets
+    echo "Setting permissions on ZFS datasets..."
+    chmod 1777 "$TARGET/tmp"
+    chmod 1777 "$TARGET/var/tmp"
+    echo "✓ Temp directory permissions set (1777)"
+}
+
+function set_final_mountpoints {
+    echo "======= Setting final mountpoints =========="
+    
+    # Leaf datasets - actual system mountpoints
+    zfs set mountpoint=/tmp "$ZFS_POOL/ROOT/ubuntu/tmp"
+    zfs set mountpoint=/var/tmp "$ZFS_POOL/ROOT/ubuntu/var/tmp"
+    zfs set mountpoint=/var/log "$ZFS_POOL/ROOT/ubuntu/var/log"
+    zfs set mountpoint=/var/cache/apt "$ZFS_POOL/ROOT/ubuntu/var/cache/apt"
+    
+    # Home dataset - separate from OS
+    zfs set mountpoint=/home "$ZFS_POOL/home"    
+    echo ""
+    echo "Detailed dataset listing:"
+    zfs list -o name,mountpoint -r "$ZFS_POOL"
+}
+
+# ---- System Bootstrap Functions ----
+function bootstrap_ubuntu_system {
+    echo "======= Bootstrapping Ubuntu to temporary directory =========="
+    local TEMP_STAGE=$(mktemp -d)
+    echo "Created temporary staging directory: $TEMP_STAGE"
+    
+    # Cleanup function for temp directory
+    cleanup_temp_stage() {
+        if [ -d "$TEMP_STAGE" ]; then
+            echo "Cleaning up temporary staging directory..."
+            rm -rf "$TEMP_STAGE"
+        fi
+    }
+    
+    # Add trap to ensure cleanup on script exit
+    trap cleanup_temp_stage EXIT
+    
+    # Add Hetzner Ubuntu mirror as trusted
+    echo "deb [trusted=yes] http://mirror.hetzner.com/ubuntu/packages noble main" > /etc/apt/sources.list.d/ubuntu-temp.list
+
+    # Update and download ubuntu-keyring without sandbox warning
+    apt-get update
+    apt-get -o APT::Sandbox::User=root download ubuntu-keyring
+
+    # Verify download was successful
+    if [ ! -f ubuntu-keyring*.deb ]; then
+        echo "ERROR: Failed to download ubuntu-keyring package"
+        exit 1
+    fi
+
+    # Extract the keyring
+    dpkg-deb -x ubuntu-keyring*.deb /tmp/ubuntu-keyring-extract/
+    mkdir -p /usr/share/keyrings
+    cp /tmp/ubuntu-keyring-extract/usr/share/keyrings/ubuntu-archive-keyring.gpg /usr/share/keyrings/
+
+    echo "✓ Downloaded and extracted ubuntu-keyring package"
+
+    # Clean up - remove temporary repository and restore apt state
+    rm -f /etc/apt/sources.list.d/ubuntu-temp.list
+    apt update
+
+    # Clean up downloaded package
+    rm -f ubuntu-keyring*.deb
+
+    apt install -y mmdebstrap
+
+    mmdebstrap --variant=debootstrap \
+      --keyring=/usr/share/keyrings/ubuntu-archive-keyring.gpg \
+      --include=systemd-resolved,locales,debconf-i18n,apt-utils,keyboard-configuration,console-setup,kbd,extlinux,initramfs-tools,zstd \
+      "$UBUNTU_CODENAME" "$TEMP_STAGE" \
+      "$MIRROR_MAIN" "$MIRROR_UPDATES" "$MIRROR_BACKPORTS" "$MIRROR_SECURITY"
+
+    echo "======= Copying staged system to ZFS datasets =========="
+    # Mount root dataset for copying
+    mkdir -p "$TARGET"
+    mount -t zfs "$ZFS_POOL/ROOT/ubuntu" "$TARGET"
+
+    create_additional_zfs_datasets
+
+    # Use rsync to copy the entire system (this will populate all datasets)
+    echo "Copying staged system to ZFS datasets..."
+    rsync -aAX "$TEMP_STAGE/" "$TARGET/"
+
+    echo "Staged system copied successfully"
+    echo "Source size: $(du -sh "$TEMP_STAGE")"
+    echo "Target size: $(du -sh "$TARGET")"
+
+    # Clean up temp directory
+    cleanup_temp_stage
+    trap - EXIT
+}
+
+function setup_chroot_environment {
+    echo "======= Mounting virtual filesystems for chroot =========="
+    mount -t proc proc "$TARGET/proc"
+    mount -t sysfs sysfs "$TARGET/sys"
+    mount -t tmpfs tmpfs "$TARGET/run"
+    mount -t tmpfs tmpfs "$TARGET/tmp"
+    mount --bind /dev "$TARGET/dev"
+    mount --bind /dev/pts "$TARGET/dev/pts"
+
+    configure_dns_resolution
+}
+
+function configure_dns_resolution {
+    echo "======= Configuring DNS resolution =========="
+    mkdir -p "$TARGET/run/systemd/resolve"
+    
+    if command -v resolvectl >/dev/null 2>&1; then
+        echo "Getting DNS from resolvectl..."
+        
+        # First try Global DNS servers
+        local DNS_SERVERS=$(resolvectl dns | awk '
+            /^Global:/ { 
+                for(i=2; i<=NF; i++) print $i 
+            }
+        ' | head -3)
+        
+        # If Global is empty, find first non-empty link
+        if [ -z "$DNS_SERVERS" ]; then
+            echo "No global DNS servers found, searching for first non-empty link..."
+            DNS_SERVERS=$(resolvectl dns | awk '
+                /^Link [0-9]+ / && NF > 3 {
+                    for(i=4; i<=NF; i++) print $i  # Start from field 4 to skip the interface name
+                    exit  # Stop after first non-empty link
+                }
+            ')
+        fi
+        
+        if [ -n "$DNS_SERVERS" ]; then
+            # Create resolv.conf with the DNS servers
+            echo "$DNS_SERVERS" | while read -r dns; do
+                echo "nameserver $dns"
+            done > "$TARGET/run/systemd/resolve/stub-resolv.conf"
+            echo "Using DNS servers: $(echo "$DNS_SERVERS" | tr '\n' ' ')"
+        else
+            echo "ERROR: No DNS servers found in resolvectl output"
+            echo "resolvectl dns output:"
+            resolvectl dns
+            echo "Cannot continue without DNS configuration"
+            exit 1
+        fi
+    else
+        echo "ERROR: resolvectl command not found"
+        echo "Cannot configure DNS without resolvectl"
+        exit 1
+    fi
+}
+
+# ---- System Configuration Functions ----
+function configure_basic_system {
+    echo "======= Configuring basic system settings =========="
+    chroot "$TARGET" /bin/bash <<EOF
+set -euo pipefail
+
+# Set hostname from variable
+echo "$SYSTEM_HOSTNAME" > /etc/hostname
+
+# Configure timezone (Vienna)
+echo "Europe/Vienna" > /etc/timezone
+ln -sf /usr/share/zoneinfo/Europe/Vienna /etc/localtime
+
+# Generate locales
+cat > /etc/locale.gen <<'LOCALES'
+en_US.UTF-8 UTF-8
+de_AT.UTF-8 UTF-8
+fr_FR.UTF-8 UTF-8  
+ru_RU.UTF-8 UTF-8
+LOCALES
+
+locale-gen
+
+# Set default locale
+update-locale LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
+
+# Configure keyboard for German and US with Alt+Shift toggle
+cat > /etc/default/keyboard <<'KEYBOARD'
+# KEYBOARD CONFIGURATION FILE
+
+# Consult the keyboard(5) manual page.
+
+XKBMODEL="pc105"
+XKBLAYOUT="de,ru"
+XKBVARIANT=","
+XKBOPTIONS="grp:ctrl_shift_toggle"
+
+BACKSPACE="guess"
+KEYBOARD
+
+# Apply keyboard configuration to console
+setupcon --force
+
+# Update /etc/hosts with the hostname
+echo "127.0.0.1 localhost" > /etc/hosts
+echo "127.0.1.1 $SYSTEM_HOSTNAME" >> /etc/hosts
+echo "::1 localhost ip6-localhost ip6-loopback" >> /etc/hosts
+echo "ff02::1 ip6-allnodes" >> /etc/hosts
+echo "ff02::2 ip6-allrouters" >> /etc/hosts
+
+# Set proper permissions for ZFS datasets
+chmod 1777 /tmp
+chmod 1777 /var/tmp
+EOF
+
+    echo "======= Configuration Summary ======="
+    chroot "$TARGET" /bin/bash <<'EOF'
+echo "Hostname: $(cat /etc/hostname)"
+echo "Timezone: $(cat /etc/timezone)"
+echo "Current time: $(date)"
+echo "Default locale: $(grep LANG /etc/default/locale)"
+echo "Available locales:"
+locale -a | grep -E "(en_US|de_AT|fr_FR|ru_RU)"
+echo "Keyboard layout: $(grep XKBLAYOUT /etc/default/keyboard)"
+EOF
+}
+
+function install_system_packages {
+    echo "======= Installing ZFS and essential packages in chroot =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+# Update package lists
+apt update
+
+# Install generic kernel (creates files in ZFS dataset /boot)
+apt install -y --no-install-recommends linux-image-generic linux-headers-generic
+
+# Install ZFS utilities and aux packages
+
+echo "zfs-dkms zfs-dkms/note-incompatible-licenses note true" | debconf-set-selections
+
+apt install -y zfs-dkms zfsutils-linux zfs-initramfs software-properties-common bash curl nano htop net-tools ssh
+
+# Ensure ZFS module is included in initramfs
+echo "zfs" >> /etc/initramfs-tools/modules
+
+# Generate initramfs with ZFS support
+update-initramfs -u -k all
+
+# Verify kernel installation
+echo "Installed kernel packages:"
+dpkg -l | grep linux-image
+echo "Kernel version:"
+ls /lib/modules/
+echo "Kernel files in ZFS dataset:"
+ls -la /boot/vmlinuz* /boot/initrd.img* 2>/dev/null || echo "No kernel files found"
+EOF
+}
+
+function configure_ssh {
+    echo "======= Setting up OpenSSH =========="
+    mkdir -p "$TARGET/root/.ssh/"
+    cp /root/.ssh/authorized_keys "$TARGET/root/.ssh/authorized_keys"
+    sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' "$TARGET/etc/ssh/sshd_config"
+    sed -i 's/#PubkeyAuthentication yes/PubkeyAuthentication yes/g' "$TARGET/etc/ssh/sshd_config"
+
+    chroot "$TARGET" /bin/bash <<'EOF'
+rm /etc/ssh/ssh_host_*
+dpkg-reconfigure openssh-server -f noninteractive
+EOF
+}
+
+function set_root_credentials {
+    echo "======= Setting root password =========="
+    chroot "$TARGET" /bin/bash -c "echo root:$(printf "%q" "$ROOT_PASSWORD") | chpasswd"
+
+    echo "============ Setting up root prompt ============"
+    cat > "$TARGET/root/.bashrc" <<CONF
+export PS1='\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;32m\]\h \[\033[01;33m\]\w \[\033[01;35m\]\$ \[\033[00m\]'
+umask 022
+export LS_OPTIONS='--color=auto -h'
+eval "\$(dircolors)"
+CONF
+}
+
+# ---- Bootloader Functions ----
+function setup_efi_boot {
+    echo "======= Setting up EFI boot =========="
+    
+    # Mount EFI System Partition
+    mkdir -p "$MAIN_BOOT"
+    mount "$BOOT_PART" "$MAIN_BOOT"
+    
+    # Create EFI directory structure    
+    mkdir -p "$MAIN_BOOT/EFI/Boot"
+    
+    # Download ZFSBootMenu EFI binary
+    echo "Downloading ZFSBootMenu EFI binary from: $ZBM_EFI_URL"
+    curl -L "$ZBM_EFI_URL" -o "$MAIN_BOOT/EFI/Boot/bootx64.efi"    
+}
+
+function setup_bios_boot {
+    echo "======= Setting up BIOS boot =========="
+    
+    # Mount boot partition
+    mkdir -p "$MAIN_BOOT"
+    mount "$BOOT_PART" "$MAIN_BOOT"
+    
+    # Install extlinux in rescue system if needed
+    if ! command -v extlinux &> /dev/null; then
+        echo "Installing extlinux in rescue system..."
+        apt update
+        apt install -y extlinux
+    fi
+    
+    # Install extlinux
+    extlinux --install "$MAIN_BOOT"
+    
+    # Create extlinux configuration
+    cat > "$MAIN_BOOT/extlinux.conf" << 'EOF'
+DEFAULT zfsbootmenu
+PROMPT 0
+TIMEOUT 0
+
+LABEL zfsbootmenu
+    LINUX /zfsbootmenu/vmlinuz-bootmenu
+    INITRD /zfsbootmenu/initramfs-bootmenu.img
+    APPEND ro quiet
+EOF
+
+    echo "Generated extlinux.conf:"
+    cat "$MAIN_BOOT/extlinux.conf"
+    
+    # Download and install ZFSBootMenu for BIOS
+    local TEMP_ZBM=$(mktemp -d)
+    echo "Downloading ZFSBootMenu for BIOS from: $ZBM_BIOS_URL"
+    curl -L "$ZBM_BIOS_URL" -o "$TEMP_ZBM/zbm.tar.gz"
+    tar -xz -C "$TEMP_ZBM" -f "$TEMP_ZBM/zbm.tar.gz" --strip-components=1
+    
+    # Copy ZFSBootMenu to boot partition
+    mkdir -p "$MAIN_BOOT/zfsbootmenu"
+    cp "$TEMP_ZBM"/vmlinuz* "$MAIN_BOOT/zfsbootmenu/"
+    cp "$TEMP_ZBM"/initramfs* "$MAIN_BOOT/zfsbootmenu/"
+    
+    # Clean up
+    rm -rf "$TEMP_ZBM"
+    
+    echo "ZFSBootMenu files copied to boot partition:"
+    ls -la "$MAIN_BOOT/zfsbootmenu/"
+    
+    # Install MBR and set boot flag
+    dd bs=440 conv=notrunc count=1 if="$TARGET/usr/lib/EXTLINUX/gptmbr.bin" of="$INSTALL_DISK"
+    parted "$INSTALL_DISK" set 1 boot on
+    
+    echo "BIOS boot setup complete"
+}
+
+function configure_bootloader {
+    echo "======= Setting up boot based on firmware type =========="
+    if [ "$EFI_MODE" = true ]; then
+        setup_efi_boot
+    else
+        setup_bios_boot
+    fi
+
+    echo "======= Configuring ZFSBootMenu for auto-detection =========="
+    zfs set org.zfsbootmenu:commandline="ro quiet" "$ZFS_POOL/ROOT/ubuntu"
+
+    echo "Boot configuration:"
+    zfs get org.zfsbootmenu:commandline "$ZFS_POOL/ROOT/ubuntu"
+}
+
+# ---- System Services Functions ----
+function configure_system_services {
+    echo "======= Configuring ZFS cachefile in chrooted system =========="
+    mkdir -p "$TARGET/etc/zfs"
+    cp /etc/zfs/zpool.cache "$TARGET/etc/zfs/zpool.cache"
+
+    echo "Cachefile status:"
+    zpool get cachefile "$ZFS_POOL"
+    ls -la "$TARGET/etc/zfs/zpool.cache" && echo "✓ Cachefile ready" || echo "✗ Cachefile failed"
+
+    echo "======= Enabling essential system services =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+
+systemctl enable systemd-resolved
+systemctl enable systemd-timesyncd
+
+systemctl enable zfs-import-cache
+systemctl enable zfs-mount
+
+systemctl enable ssh
+systemctl enable apt-daily.timer
+
+echo "Enabled services:"
+systemctl list-unit-files | grep enabled
+EOF
+}
+
+function configure_networking {
+    echo "======= Configuring Netplan for Hetzner Cloud =========="
+    chroot "$TARGET" /bin/bash <<'EOF'
+set -euo pipefail
+# Create Netplan configuration that matches all non-loopback interfaces
+cat > /etc/netplan/01-hetzner.yaml <<'EOL'
+network:
+  version: 2
+  renderer: networkd
+  ethernets:
+    all-interfaces:
+      match:
+        name: "!lo"
+      dhcp4: true
+      dhcp6: true
+      dhcp4-overrides:
+        use-dns: true
+        use-hostname: true
+        use-domains: true
+        route-metric: 100
+      dhcp6-overrides:
+        use-dns: true
+        use-hostname: true
+        use-domains: true
+        route-metric: 100
+      critical: true
+EOL
+
+# Set proper permissions - Netplan requires strict permissions (600)
+chmod 600 /etc/netplan/01-hetzner.yaml
+chown root:root /etc/netplan/01-hetzner.yaml
+
+# Apply the Netplan configuration
+netplan generate
+echo "Netplan configuration created for all interfaces"
+EOF
+}
+
+# ---- Cleanup and Finalization Functions ----
+function unmount_all_datasets_and_partitions {
+    echo "======= Unmounting all datasets =========="
+    
+    # First, unmount all auto-mounted ZFS datasets (tmp, var/tmp, var/log, etc.)
+    echo "Unmounting auto-mounted ZFS datasets..."
+    zfs umount -a 2>/dev/null || true
+    
+    # Manually unmount the root legacy dataset from $TARGET
+    if mountpoint -q "$TARGET"; then
+        echo "Unmounting root dataset from $TARGET"
+        umount "$TARGET" 2>/dev/null || true
+    fi
+    
+    # Manually unmount boot partition if mounted
+    if mountpoint -q "$MAIN_BOOT"; then
+        echo "Unmounting boot partition from $MAIN_BOOT"
+        umount "$MAIN_BOOT" 2>/dev/null || true
+    fi
+    
+    # Wait for unmounts to complete
+    sleep 1
+    
+    # Force unmount any stubborn datasets
+    if zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep -q "yes"; then
+        echo "Forcing unmount of remaining ZFS datasets..."
+        zfs umount -a -f 2>/dev/null || true
+    fi
+    
+    # Final verification
+    local mounted_count=0
+    mounted_count=$(zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep -c "yes" || true)
+    
+    if [ "$mounted_count" -gt 0 ]; then
+        echo "WARNING: $mounted_count dataset(s) still mounted after unmount attempt:"
+        zfs get mounted -r "$ZFS_POOL" 2>/dev/null | grep "yes" || true
+    else
+        echo "✓ All ZFS datasets successfully unmounted"
+    fi
+    
+    # Verify $TARGET is unmounted
+    if mountpoint -q "$TARGET"; then
+        echo "WARNING: $TARGET is still mounted!"
+        mount | grep "$TARGET" || true
+    else
+        echo "✓ $TARGET successfully unmounted"
+    fi
+    
+    # Verify $MAIN_BOOT is unmounted
+    if mountpoint -q "$MAIN_BOOT"; then
+        echo "WARNING: $MAIN_BOOT is still mounted!"
+        mount | grep "$MAIN_BOOT" || true
+    else
+        echo "✓ $MAIN_BOOT successfully unmounted"
+    fi
+}
+
+function unmount_chroot_environment {
+    echo "======= Unmounting virtual filesystems =========="
+    # Unmount virtual filesystems first
+    for dir in dev/pts dev tmp run sys proc; do
+        if mountpoint -q "$TARGET/$dir"; then
+            echo "Unmounting $TARGET/$dir"
+            umount "$TARGET/$dir" 2>/dev/null || true
+        fi
+    done
+}
+
+function finalize_system_resolved {
+    echo "======= Setting systemd-resolved configuration for final boot =========="
+    # This must be done while $TARGET is still mounted
+    mkdir -p "$TARGET/run/systemd/resolve"
+    cat > "$TARGET/run/systemd/resolve/stub-resolv.conf" << 'EOF'
+nameserver 127.0.0.53
+options edns0 trust-ad
+search .
+EOF
+    echo "✓ systemd-resolved configuration set"
+}
+
+function export_zfs_pool {
+    echo "======= Exporting ZFS pool =========="
+    zpool export "$ZFS_POOL" 2>/dev/null || true
+
+    # Verify everything is unmounted
+    if mountpoint -q "$TARGET"; then
+        echo "WARNING: $TARGET is still mounted!"
+        mount | grep "$TARGET"
+    else
+        echo "✓ All filesystems successfully unmounted"
+    fi
+}
+
+function show_final_instructions {
+    echo ""
+    echo "=========================================="
+    echo "  INSTALLATION COMPLETE! "
+    echo "=========================================="
+    echo ""
+    echo "System Information:"
+    echo "  Hostname: $SYSTEM_HOSTNAME"
+    echo "  ZFS Pool: $ZFS_POOL"
+    echo "  Boot Mode: $([ "$EFI_MODE" = true ] && echo "EFI" || echo "BIOS")"
+    echo "  Ubuntu Version: $UBUNTU_CODENAME"
+    echo "  Networking: systemd-networkd + systemd-resolved"    
+    echo ""
+    echo "=========================================="
+    echo "Rebooting..."
+}
+
+# ---- Main Execution Function ----
+function main {
+    echo "Starting ZFS Ubuntu installation on Hetzner Cloud..."
+    
+    # Phase 0: User input
+    get_user_input
+    
+    # Phase 1: System detection and preparation
+    detect_efi
+    find_install_disk
+    
+    # Show summary and get final confirmation
+    show_summary_and_confirm
+    
+    remove_unused_kernels
+    install_zfs_on_rescue_system
+    
+    # Phase 2: Disk partitioning and ZFS setup
+    partition_disk
+    create_zfs_pool
+    
+    # Phase 3: System bootstrap
+    bootstrap_ubuntu_system
+    setup_chroot_environment
+    
+    # Phase 4: System configuration
+    configure_basic_system
+    install_system_packages
+    configure_ssh
+    set_root_credentials
+    configure_system_services
+    configure_networking
+    
+    # Phase 5: Bootloader setup
+    configure_bootloader
+    
+    # Phase 6: Cleanup and finalization
+    unmount_chroot_environment
+    finalize_system_resolved    
+    unmount_all_datasets_and_partitions
+    
+    # Phase 7: Final mountpoints and export    
+    set_final_mountpoints
+    
+    export_zfs_pool
+    
+    show_final_instructions
+
+    reboot
+}
+
+# Execute main function
+main "$@"