.. highlight:: sh

.. ifconfig:: zfs_root_test

 ::

  # For the CI/CD test run of this guide,
  # Enable verbose logging of bash shell and fail immediately when
  # a commmand fails.
  set -vxeuf
  distro=${1}

  cp /etc/resolv.conf ./"rootfs-${distro}"/etc/resolv.conf
  arch-chroot ./"rootfs-${distro}" sh <<-'ZFS_ROOT_GUIDE_TEST'

  set -vxeuf

  # install alpine setup scripts
  apk update
  apk add alpine-conf curl

.. In this document, there are three types of code-block markups:
   ``::`` are commands intended for both the vm test and the users
   ``.. ifconfig:: zfs_root_test`` are commands intended only for vm test
   ``.. code-block:: sh`` are commands intended only for users

Arch Linux Root on ZFS
=======================================

**Customization**

Unless stated otherwise, it is not recommended to customize system
configuration before reboot.

Preparation
---------------------------

#. Disable Secure Boot. ZFS modules can not be loaded if Secure Boot is enabled.
#. Because the kernel of latest Live CD might be incompatible with
   ZFS, we will use Alpine Linux Extended, which ships with ZFS by
   default.

   Download latest extended variant of `Alpine Linux
   live image
   <https://dl-cdn.alpinelinux.org/alpine/v3.17/releases/x86_64/alpine-extended-3.17.3-x86_64.iso>`__,
   verify `checksum <https://dl-cdn.alpinelinux.org/alpine/v3.17/releases/x86_64/alpine-extended-3.17.3-x86_64.iso.asc>`__
   and boot from it.

   .. code-block:: sh

       gpg --auto-key-retrieve --keyserver hkps://keyserver.ubuntu.com --verify alpine-extended-*.asc

       dd if=input-file of=output-file bs=1M

   .. ifconfig:: zfs_root_test

     # check whether the download page exists
      # alpine version must be in sync with ci/cd test chroot tarball

#. Login as root user.  There is no password.
#. Configure Internet

   .. code-block:: sh

     setup-interfaces -r
     # You must use "-r" option to start networking services properly
     # example:
     network interface: wlan0
     WiFi name:         <ssid>
     ip address:        dhcp
     <enter done to finish network config>
     manual netconfig:  n

#. If you are using wireless network and it is not shown, see `Alpine
   Linux wiki
   <https://wiki.alpinelinux.org/wiki/Wi-Fi#wpa_supplicant>`__ for
   further details.  ``wpa_supplicant`` can be installed with ``apk
   add wpa_supplicant`` without internet connection.

#. Configure SSH server

   .. code-block:: sh

     setup-sshd
     # example:
     ssh server:        openssh
     allow root:        "prohibit-password" or "yes"
     ssh key:           "none" or "<public key>"

#. Set root password or ``/root/.ssh/authorized_keys``.

#. Connect from another computer

   .. code-block:: sh

    ssh root@192.168.1.91

#. Configure NTP client for time synchronization

   .. code-block:: sh

     setup-ntp busybox

   .. ifconfig:: zfs_root_test

     # this step is unnecessary for chroot and returns 1 when executed

#. Set up apk-repo.  A list of available mirrors is shown.
   Press space bar to continue

   .. code-block:: sh

    setup-apkrepos

#. Throughout this guide, we use predictable disk names generated by
   udev

   .. code-block:: sh

     apk update
     apk add eudev
     setup-devd udev

   .. ifconfig:: zfs_root_test

      # for some reason, udev is extremely slow in chroot
      # it is not needed for chroot anyway. so, skip this step

#. Target disk

   List available disks with

   .. code-block:: sh

    find /dev/disk/by-id/

   If virtio is used as disk bus, power off the VM and set serial numbers for disk.
   For QEMU, use ``-drive format=raw,file=disk2.img,serial=AaBb``.
   For libvirt, edit domain XML.  See `this page
   <https://bugzilla.redhat.com/show_bug.cgi?id=1245013>`__ for examples.

   Declare disk array

   .. code-block:: sh

    DISK='/dev/disk/by-id/ata-FOO /dev/disk/by-id/nvme-BAR'

   For single disk installation, use

   .. code-block:: sh

    DISK='/dev/disk/by-id/disk1'

   .. ifconfig:: zfs_root_test

    # for github test run, use chroot and loop devices
    DISK="$(losetup -a| grep archlinux | cut -f1 -d: | xargs -t -I '{}' printf '{} ')"

#. Set a mount point
   ::

      MNT=$(mktemp -d)

#. Set partition size:

   Set swap size in GB, set to 1 if you don't want swap to
   take up too much space

   .. code-block:: sh

    SWAPSIZE=4

   .. ifconfig:: zfs_root_test

    # For the test run, use 1GB swap space to avoid hitting CI/CD
    # quota
    SWAPSIZE=1

   Set how much space should be left at the end of the disk, minimum 1GB

   ::

    RESERVE=1

#. Install ZFS support from live media::

    apk add zfs

#. Install partition tool
   ::

      apk add parted e2fsprogs cryptsetup util-linux

System Installation
---------------------------

#. Partition the disks.

   Note: you must clear all existing partition tables and data structures from the disks,
   especially those with existing ZFS pools or mdraid and those that have been used as live media.
   Those data structures may interfere with boot process.

   For flash-based storage, this can be done by uncommenting the blkdiscard command below:
   ::

     partition_disk () {
      local disk="${1}"
      #blkdiscard -f "${disk}"

      parted --script --align=optimal  "${disk}" -- \
      mklabel gpt \
      mkpart EFI 2MiB 1GiB \
      mkpart bpool 1GiB 5GiB \
      mkpart rpool 5GiB -$((SWAPSIZE + RESERVE))GiB \
      mkpart swap  -$((SWAPSIZE + RESERVE))GiB -"${RESERVE}"GiB \
      mkpart BIOS 1MiB 2MiB \
      set 1 esp on \
      set 5 bios_grub on \
      set 5 legacy_boot on

      partprobe "${disk}"
     }

     for i in ${DISK}; do
        partition_disk "${i}"
     done

   .. ifconfig:: zfs_root_test

     ::

       # When working with GitHub chroot runners, we are using loop
       # devices as installation target.  However, the alias support for
       # loop device was just introduced in March 2023. See
       # https://github.com/systemd/systemd/pull/26693
       # For now, we will create the aliases maunally as a workaround
       looppart="1 2 3 4 5"
       for i in ${DISK}; do
         for j in ${looppart}; do
           if test -e "${i}p${j}"; then
                    ln -s "${i}p${j}" "${i}-part${j}"
                  fi
         done
       done

#. Setup encrypted swap.  This is useful if the available memory is
   small::

     for i in ${DISK}; do
        cryptsetup open --type plain --key-file /dev/random "${i}"-part4 "${i##*/}"-part4
        mkswap /dev/mapper/"${i##*/}"-part4
        swapon /dev/mapper/"${i##*/}"-part4
     done

#. Load ZFS kernel module

   .. code-block:: sh

       modprobe zfs

#. Create boot pool
   ::

      # shellcheck disable=SC2046
      zpool create -d \
          -o feature@async_destroy=enabled \
          -o feature@bookmarks=enabled \
          -o feature@embedded_data=enabled \
          -o feature@empty_bpobj=enabled \
          -o feature@enabled_txg=enabled \
          -o feature@extensible_dataset=enabled \
          -o feature@filesystem_limits=enabled \
          -o feature@hole_birth=enabled \
          -o feature@large_blocks=enabled \
          -o feature@lz4_compress=enabled \
          -o feature@spacemap_histogram=enabled \
          -o ashift=12 \
          -o autotrim=on \
          -O acltype=posixacl \
          -O canmount=off \
          -O compression=lz4 \
          -O devices=off \
          -O normalization=formD \
          -O relatime=on \
          -O xattr=sa \
          -O mountpoint=/boot \
          -R "${MNT}" \
          bpool \
                 mirror \
          $(for i in ${DISK}; do
             printf '%s ' "${i}-part2";
            done)

   If not using a multi-disk setup, remove ``mirror``.

   You should not need to customize any of the options for the boot pool.

   GRUB does not support all of the zpool features. See ``spa_feature_names``
   in `grub-core/fs/zfs/zfs.c
   <http://git.savannah.gnu.org/cgit/grub.git/tree/grub-core/fs/zfs/zfs.c#n276>`__.
   This step creates a separate boot pool for ``/boot`` with the features
   limited to only those that GRUB supports, allowing the root pool to use
   any/all features.

#. Create root pool
   ::

       # shellcheck disable=SC2046
       zpool create \
           -o ashift=12 \
           -o autotrim=on \
           -R "${MNT}" \
           -O acltype=posixacl \
           -O canmount=off \
           -O compression=zstd \
           -O dnodesize=auto \
           -O normalization=formD \
           -O relatime=on \
           -O xattr=sa \
           -O mountpoint=/ \
           rpool \
           mirror \
          $(for i in ${DISK}; do
             printf '%s ' "${i}-part3";
            done)

   If not using a multi-disk setup, remove ``mirror``.

#. Create root system container:

   - Unencrypted

     ::

      zfs create \
       -o canmount=off \
       -o mountpoint=none \
      rpool/archlinux

   - Encrypted:

     Pick a strong password. Once compromised, changing password will not keep your
     data safe. See ``zfs-change-key(8)`` for more info

     .. code-block:: sh

      zfs create \
        -o canmount=off \
               -o mountpoint=none \
               -o encryption=on \
               -o keylocation=prompt \
               -o keyformat=passphrase \
      rpool/archlinux

   You can automate this step (insecure) with: ``echo POOLPASS | zfs create ...``.

   Create system datasets,
   manage mountpoints with ``mountpoint=legacy``
   ::

      zfs create -o canmount=noauto -o mountpoint=/  rpool/archlinux/root
      zfs mount rpool/archlinux/root
      zfs create -o mountpoint=legacy rpool/archlinux/home
      mkdir "${MNT}"/home
      mount -t zfs rpool/archlinux/home "${MNT}"/home
      zfs create -o mountpoint=legacy  rpool/archlinux/var
      zfs create -o mountpoint=legacy rpool/archlinux/var/lib
      zfs create -o mountpoint=legacy rpool/archlinux/var/log
      zfs create -o mountpoint=none bpool/archlinux
      zfs create -o mountpoint=legacy bpool/archlinux/root
      mkdir "${MNT}"/boot
      mount -t zfs bpool/archlinux/root "${MNT}"/boot
      mkdir -p "${MNT}"/var/log
      mkdir -p "${MNT}"/var/lib
      mount -t zfs rpool/archlinux/var/lib "${MNT}"/var/lib
      mount -t zfs rpool/archlinux/var/log "${MNT}"/var/log

#. Format and mount ESP
   ::

     for i in ${DISK}; do
      mkfs.vfat -n EFI "${i}"-part1
      mkdir -p "${MNT}"/boot/efis/"${i##*/}"-part1
      mount -t vfat -o iocharset=iso8859-1 "${i}"-part1 "${MNT}"/boot/efis/"${i##*/}"-part1
     done

     mkdir -p "${MNT}"/boot/efi
     mount -t vfat -o iocharset=iso8859-1 "$(echo "${DISK}" | sed "s|^ *||"  | cut -f1 -d' '|| true)"-part1 "${MNT}"/boot/efi

System Configuration 
---------------------------

#. Download and extract minimal Arch Linux root filesystem::

     apk add curl

     curl --fail-early --fail -L \
     https://america.archive.pkgbuild.com/iso/2023.04.01/archlinux-bootstrap-x86_64.tar.gz \
     -o rootfs.tar.gz
     curl --fail-early --fail -L \
     https://america.archive.pkgbuild.com/iso/2023.04.01/archlinux-bootstrap-x86_64.tar.gz.sig \
     -o rootfs.tar.gz.sig

     apk add gnupg
     gpg --auto-key-retrieve --keyserver hkps://keyserver.ubuntu.com --verify rootfs.tar.gz.sig

     ln -s "${MNT}" "${MNT}"/root.x86_64
     tar x  -C "${MNT}" -af rootfs.tar.gz root.x86_64

#. Enable community repo

   .. code-block:: sh

    sed -i '/edge/d' /etc/apk/repositories
    sed -i -E 's/#(.*)community/\1community/' /etc/apk/repositories

#. Generate fstab::

    apk add arch-install-scripts
    genfstab -t PARTUUID "${MNT}" \
    | grep -v swap \
    | sed "s|vfat.*rw|vfat rw,x-systemd.idle-timeout=1min,x-systemd.automount,noauto,nofail|" \
    > "${MNT}"/etc/fstab

#. Chroot

   .. code-block:: sh

    cp /etc/resolv.conf "${MNT}"/etc/resolv.conf
    for i in /dev /proc /sys; do mkdir -p "${MNT}"/"${i}"; mount --rbind "${i}" "${MNT}"/"${i}"; done
    chroot "${MNT}" /usr/bin/env DISK="${DISK}" bash

   .. ifconfig:: zfs_root_test

    ::

     cp /etc/resolv.conf "${MNT}"/etc/resolv.conf
     for i in /dev /proc /sys; do mkdir -p "${MNT}"/"${i}"; mount --rbind "${i}" "${MNT}"/"${i}"; done
     chroot "${MNT}" /usr/bin/env DISK="${DISK}" bash <<-'ZFS_ROOT_NESTED_CHROOT'

     set -vxeuf

#. Add archzfs repo to pacman config

   ::

       pacman-key --init
       pacman-key --refresh-keys
       pacman-key --populate

       curl --fail-early --fail -L https://archzfs.com/archzfs.gpg \
       |  pacman-key -a - --gpgdir /etc/pacman.d/gnupg

       pacman-key \
       --lsign-key \
       --gpgdir /etc/pacman.d/gnupg \
       DDF7DB817396A49B2A2723F7403BD972F75D9D76

       tee -a /etc/pacman.d/mirrorlist-archzfs <<- 'EOF'
       ## See https://github.com/archzfs/archzfs/wiki
       ## France
       #,Server = https://archzfs.com/$repo/$arch

       ## Germany
       #,Server = https://mirror.sum7.eu/archlinux/archzfs/$repo/$arch
       #,Server = https://mirror.biocrafting.net/archlinux/archzfs/$repo/$arch

       ## India
       #,Server = https://mirror.in.themindsmaze.com/archzfs/$repo/$arch

       ## United States
       #,Server = https://zxcvfdsa.com/archzfs/$repo/$arch
       EOF

       tee -a /etc/pacman.conf <<- 'EOF'

       #[archzfs-testing]
       #Include = /etc/pacman.d/mirrorlist-archzfs

       #,[archzfs]
       #,Include = /etc/pacman.d/mirrorlist-archzfs
       EOF

       # this #, prefix is a workaround for ci/cd tests
       # remove them
       sed -i 's|#,||' /etc/pacman.d/mirrorlist-archzfs
       sed -i 's|#,||' /etc/pacman.conf
       sed -i 's|^#||' /etc/pacman.d/mirrorlist

#. Install base packages::

     pacman -Sy
     pacman -S --noconfirm mg mandoc grub efibootmgr mkinitcpio

     kernel_compatible_with_zfs="$(pacman -Si zfs-linux \
     | grep 'Depends On' \
     | sed "s|.*linux=||" \
     | awk '{ print $1 }')"
     pacman -U --noconfirm https://america.archive.pkgbuild.com/packages/l/linux/linux-"${kernel_compatible_with_zfs}"-x86_64.pkg.tar.zst

#. Install zfs packages::

     pacman -S --noconfirm zfs-linux zfs-utils


#. Configure mkinitcpio::

     sed -i 's|filesystems|zfs filesystems|' /etc/mkinitcpio.conf
     mkinitcpio -P

#. For physical machine, install firmware

   .. code-block:: sh

     pacman -S linux-firmware intel-ucode amd-ucode

#. Enable internet time synchronisation::

     systemctl enable systemd-timesyncd

#. Generate host id::

    zgenhostid -f -o /etc/hostid

#. Generate locales::

    echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
    locale-gen

#. Set locale, keymap, timezone, hostname

   ::

    rm -f /etc/localtime
    systemd-firstboot \
    --force \
    --locale=en_US.UTF-8 \
    --timezone=Etc/UTC \
    --hostname=testhost \
    --keymap=us

#. Set root passwd
   ::

    printf 'root:yourpassword' | chpasswd

Bootloader
---------------------------


#. Apply GRUB workaround

   ::

     echo 'export ZPOOL_VDEV_NAME_PATH=YES' >> /etc/profile.d/zpool_vdev_name_path.sh
     # shellcheck disable=SC1091
     . /etc/profile.d/zpool_vdev_name_path.sh

     # GRUB fails to detect rpool name, hard code as "rpool"
     sed -i "s|rpool=.*|rpool=rpool|"  /etc/grub.d/10_linux

   This workaround needs to be applied for every GRUB update, as the
   update will overwrite the changes.

#. Install GRUB::

      mkdir -p /boot/efi/archlinux/grub-bootdir/i386-pc/
      mkdir -p /boot/efi/archlinux/grub-bootdir/x86_64-efi/
      for i in ${DISK}; do
       grub-install --target=i386-pc --boot-directory \
           /boot/efi/archlinux/grub-bootdir/i386-pc/  "${i}"
      done
      grub-install --target x86_64-efi --boot-directory \
       /boot/efi/archlinux/grub-bootdir/x86_64-efi/ --efi-directory \
       /boot/efi --bootloader-id archlinux --removable
      if test -d /sys/firmware/efi/efivars/; then
         grub-install --target x86_64-efi --boot-directory \
          /boot/efi/archlinux/grub-bootdir/x86_64-efi/ --efi-directory \
          /boot/efi --bootloader-id archlinux
      fi


#. Import both bpool and rpool at boot::

     echo 'GRUB_CMDLINE_LINUX="zfs_import_dir=/dev/"' >> /etc/default/grub

#. Generate GRUB menu::

     mkdir -p /boot/grub
     grub-mkconfig -o /boot/grub/grub.cfg
     cp /boot/grub/grub.cfg \
      /boot/efi/archlinux/grub-bootdir/x86_64-efi/grub/grub.cfg
     cp /boot/grub/grub.cfg \
      /boot/efi/archlinux/grub-bootdir/i386-pc/grub/grub.cfg

   .. ifconfig:: zfs_root_test

      ::

         find /boot/efis/ -name "grub.cfg" -print0 \
         | xargs -t -0I '{}' grub-script-check -v '{}'

#. For both legacy and EFI booting: mirror ESP content::

    espdir=$(mktemp -d)
    find /boot/efi/ -maxdepth 1 -mindepth 1 -type d -print0 \
    | xargs -t -0I '{}' cp -r '{}' "${espdir}"
    find "${espdir}" -maxdepth 1 -mindepth 1 -type d -print0 \
    | xargs -t -0I '{}' sh -vxc "find /boot/efis/ -maxdepth 1 -mindepth 1 -type d -print0 | xargs -t -0I '[]' cp -r '{}' '[]'"

#. Exit chroot

   .. code-block:: sh

     exit

   .. ifconfig:: zfs_root_test

     # nested chroot ends here
     ZFS_ROOT_NESTED_CHROOT

   .. ifconfig:: zfs_root_test

    ::

     # list contents of boot dir to confirm
     # that the mirroring succeeded
     find "${MNT}"/boot/efis/ -type d > list_of_efi_dirs
     for i in ${DISK}; do
       if ! grep "${i##*/}-part1/efi\|${i##*/}-part1/EFI" list_of_efi_dirs; then
          echo "disk ${i} not found in efi system partition, installation error";
          cat list_of_efi_dirs
          exit 1
       fi
     done

#. Unmount filesystems and create initial system snapshot
   You can later create a boot environment from this snapshot.
   See `Root on ZFS maintenance page <../zfs_root_maintenance.html>`__.
   ::

    umount -Rl "${MNT}"
    zfs snapshot -r rpool@initial-installation
    zfs snapshot -r bpool@initial-installation

#. Export all pools

   .. code-block:: sh

    zpool export -a

   .. ifconfig:: zfs_root_test

    # we are now inside a chroot, where the export will fail
    # export pools when we are outside chroot

#. Reboot

   .. code-block:: sh

     reboot

   .. ifconfig:: zfs_root_test

     # chroot ends here
     ZFS_ROOT_GUIDE_TEST