nixos-zfs-installer.sh

#!/bin/sh

# exit as soon as any line in the script fails, print each command that's going to be executed
set -ex

# wipe disk
sgdisk --zap-all ${DISK}

# create GPT partition table
parted ${DISK} -- mklabel gpt
# create primary partition
parted ${DISK} -- mkpart primary 512MB -8GB
# make swap partition
parted ${DISK} -- mkpart primary linux-swap -8GB 100%
# make boot partition
parted ${DISK} -- mkpart ESP fat32 1MB 512MB
# turn on esp
parted ${DISK} -- set 3 esp on


# setup boot filesystem
mkfs.fat -F 32 -n BOOT ${DISK}-part3

# setup swap
mkswap -L swap ${DISK}-part2
swapon ${DISK}-part2

# create the zfs pool
# relevant options
# autotrim: automatic trim on occasion
# listsnapshots: includes snapshots in zfs list
# compression: zstd: use zstandard compression
zpool create -f \
      -o ashift=12 \
      -o autotrim=on \
      -o listsnapshots=on \
      -O acltype=posixacl \
      -O compression=zstd \
      -O dnodesize=auto \
      -O normalization=formD \
      -O mountpoint=none \
      -O relatime=on \
      -O xattr=sa \
      rpool \ ${DISK}-part1

# create the encrypted root system container. See https://www.reddit.com/r/zfs/comments/bnvdco/zol_080_encryption_dont_encrypt_the_pool_root/
# don't mount
zfs create -p -v \
    -o mountpoint=none \
    -o encryption=on \
    -o keylocation=prompt \
    -o keyformat=passphrase \
    rpool/nixos

# zfs dataset for nix store
zfs create -p -v \
    -o relatime=off \
    -o mountpoint=legacy \
    -o com.sun:auto-snapshot=false \
    rpool/nixos/nix

# zfs dataset for home
zfs create -p -v \
    -o mountpoint=legacy \
    -o secondarycache=none \
    -o com.sun:auto-snapshot=true \
    rpool/nixos/home

# zfs dataset for root
zfs create -p -v \
    -o mountpoint=legacy \
    -o secondarycache=none \
    -o com.sun-auto-snapshot=true \
    rpool/nixos/root

# It's not very useful to snapshot systemd logs, so that can have its
# own persistent dataset as well.
zfs create -p -v \
    -o mountpoint=legacy \
    -o secondarycache=none \
    -o com.sun:auto-snapshot=false \
    rpool/nixos/systemd-logs

# Finally, create an unused, unmounted 2 GB dataset in case the rest
# of the pool runs out of space and is unable to reclaim it (an
# unfortunate side effect of copy-on-write filesystems).
#
# If that happens, this dataset can be deleted, space can be
# reclaimed, and then it can be created again in case something
# similar happens in the future.
zfs create \
    -o refreservation=2G \
    -o primarycache=none \
    -o secondarycache=none \
    -o mountpoint=none \
    rpool/nixos/reserved

# mount root dataset
mount -t zfs rpool/nixos/root /mnt

# mount efi partition
mkdir -p /mnt/boot
mount -t vfat ${DISK}-part3 /mnt/boot

# mount home dataset
mkdir -p /mnt/home
mount -t zfs rpool/nixos/home /mnt/home

# mount nixos store
mkdir -p /mnt/nix
mount -t zfs rpool/nixos/nix /mnt/nix

# mount log dataset
mkdir -p /mnt/var/log
mount -t zfs rpool/nixos/systemd-logs /mnt/var/log

nixos-generate-config --root /mnt