17cce973fc
nixos-26.05 asserts against boot.initrd.postDeviceCommands under the systemd stage-1 initrd. Move the root-subvolume rollback into an initrd systemd oneshot (ordered after the labelled device, before sysroot.mount). Same rollback logic; awk swapped for cut since coreutils' cut is in the systemd initrd but awk is not. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
81 lines
2.4 KiB
Nix
81 lines
2.4 KiB
Nix
{ config, lib, ... }:
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{
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options.nanuqsaurus.impermanence.enable = lib.mkOption {
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type = lib.types.bool;
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default = false;
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description = "Enable impermanence with a /persist Btrfs subvolume.";
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};
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config = lib.mkIf config.nanuqsaurus.impermanence.enable {
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boot.initrd.supportedFilesystems = [ "btrfs" ];
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# Reset the /root subvolume to a pristine snapshot on every boot.
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# systemd stage-1 initrd does not support boot.initrd.postDeviceCommands, so
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# this runs as an initrd systemd service, ordered after the labelled device
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# appears and before the root filesystem is mounted (sysroot.mount).
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# Note: `cut` (coreutils) is used instead of `awk`, which is not in the
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# systemd initrd.
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boot.initrd.systemd.services.rollback = {
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description = "Rollback btrfs root subvolume to a pristine state";
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wantedBy = [ "initrd.target" ];
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after = [ "dev-disk-by\\x2dlabel-nixos.device" ];
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before = [ "sysroot.mount" ];
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unitConfig.DefaultDependencies = "no";
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serviceConfig.Type = "oneshot";
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script = ''
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mkdir -p /mnt
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mount -t btrfs -o subvol=/ /dev/disk/by-label/nixos /mnt
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if [ ! -d /mnt/root-blank ]; then
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btrfs subvolume snapshot -r /mnt/root /mnt/root-blank
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fi
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if [ -d /mnt/root ]; then
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if [ -d /mnt/root-previous ]; then
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btrfs subvolume delete /mnt/root-previous
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fi
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btrfs subvolume snapshot /mnt/root /mnt/root-previous
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while true; do
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subvols="$(btrfs subvolume list -o /mnt/root | cut -f9 -d' ')"
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if [ -z "$subvols" ]; then
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break
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fi
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for subvol in $subvols; do
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btrfs subvolume delete "/mnt/$subvol"
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done
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done
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btrfs subvolume delete /mnt/root
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fi
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btrfs subvolume snapshot /mnt/root-blank /mnt/root
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umount /mnt
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'';
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};
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fileSystems."/persist".neededForBoot = true;
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environment.persistence."/persist" = {
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hideMounts = true;
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directories = [
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"/etc/nixos"
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"/etc/NetworkManager"
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"/etc/ssh"
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"/var/lib/bluetooth"
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"/var/lib/cups"
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"/var/lib/fprint"
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"/var/lib/libvirt"
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"/var/lib/NetworkManager"
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"/var/lib/secureboot"
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"/var/lib/tailscale"
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"/var/lib/systemd"
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"/var/lib/nixos"
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];
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files = [
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"/etc/machine-id"
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];
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};
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};
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}
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