lexy: re-install using ZFS and impermanence

[dotlambda]

Doing this on another host requires setting disko.devices.disk.main.device to the correct drive and using the following script:

#! /usr/bin/env nix-shell
#! nix-shell -p nixos-anywhere -i bash

set -eu

host="$1"

tmp="/tmp/reinstall/$host"
rm -rf "$tmp"
mkdir -p "$tmp/persist/etc" "$tmp/persist/var"
rsync -aAXUH --progress "root@$host:/etc/machine-id" "$tmp/persist/etc/"
rsync -aAXUH --progress "root@$host:/etc/ssh" "$tmp/persist/etc/"
rsync -aAXUH --progress "root@$host:/var/log" "$tmp/persist/var/"

tree "$tmp"
read -p "Continue? " -n 1 -r
echo
if [[ ! "$REPLY" =~ ^[Yy]$ ]]; then
    exit 1
fi

nixos-anywhere --flake ".#$host" --target-host "root@$host" --phases kexec,disko,install

rsync -aAXUH --progress --chown 0:0 "$tmp/persist" "root@$host:/mnt/"

ssh "root@$host" sh <<EOF
umount -Rv /mnt
swapoff -a
zpool export -a || true
nohup sh -c 'sleep 6 && reboot' >/dev/null 2>&1 &
EOF

read -p "Delete local copy? " -n 1 -r
echo
if [[ "$REPLY" =~ ^[Yy]$ ]]; then
    rm -rf "$tmp"
fi