74 lines
1.8 KiB
Nix
74 lines
1.8 KiB
Nix
{
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pkgs,
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lib,
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config,
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...
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}:
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let
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cfg = config.custom.impermanence;
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in
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{
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# Import common impermanence configuration
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imports = [ ./impermanence-common.nix ];
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options.custom.impermanence = {
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enable = lib.mkOption {
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type = lib.types.bool;
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default = true;
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description = "Enable impermanent root fs with btrfs subvolume rollback";
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};
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};
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config = lib.mkIf cfg.enable {
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# Use /persist for btrfs-based impermanence
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custom.impermanence.persistPath = "/persist";
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# Btrfs-specific filesystem options
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fileSystems."/".options = [
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"compress=zstd"
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"noatime"
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];
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fileSystems."/nix".options = [
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"compress=zstd"
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"noatime"
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];
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fileSystems."/persist".options = [
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"compress=zstd"
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"noatime"
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];
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fileSystems."/persist".neededForBoot = true;
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fileSystems."/var/log".options = [
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"compress=zstd"
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"noatime"
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];
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fileSystems."/var/log".neededForBoot = true;
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# Btrfs subvolume rollback at each boot
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# Note `lib.mkBefore` is used instead of `lib.mkAfter` here.
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boot.initrd.postDeviceCommands = pkgs.lib.mkBefore ''
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mkdir /mnt
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mount ${config.fileSystems."/".device} /mnt
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if [[ -e /mnt/root ]]; then
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mkdir -p /mnt/old_roots
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timestamp=$(date --date="@$(stat -c %Y /mnt/root)" "+%Y-%m-%-d_%H:%M:%S")
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mv /mnt/root "/mnt/old_roots/$timestamp"
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fi
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delete_subvolume_recursively() {
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IFS=$'\n'
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for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
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delete_subvolume_recursively "/mnt/$i"
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done
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btrfs subvolume delete "$1"
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}
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for i in $(find /mnt/old_roots/ -maxdepth 1 -mtime +30); do
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delete_subvolume_recursively "$i"
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done
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btrfs subvolume create /mnt/root
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umount /mnt
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'';
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};
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}
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