375 lines
11 KiB
Nix
375 lines
11 KiB
Nix
{
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config,
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utils,
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pkgs,
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lib,
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...
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}:
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let
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BOOT = "/dev/disk/by-uuid/62B5-E906";
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PRIMARY = "/dev/disk/by-uuid/623488e2-efdd-40f4-86d0-0bddd8f8cb62";
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SWAP = "/dev/disk/by-uuid/4b3d00b4-f66f-4cbd-a87b-c03489212789";
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USB_KEY = "/dev/disk/by-uuid/63a7bd87-d644-43ea-83ba-547c03012fb6";
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primaryDeviceUnit = "${utils.escapeSystemdPath PRIMARY}.device";
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in
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lib.mkMerge [
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# Main filesystems
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{
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# BOOT
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fileSystems."/boot" = {
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device = BOOT;
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fsType = "vfat";
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options = [
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"fmask=0022"
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"dmask=0022"
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];
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};
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# PRIMARY
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fileSystems."/" = {
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device = PRIMARY;
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fsType = "bcachefs";
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options = [
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"X-mount.subdir=@root"
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# "x-systemd.requires=unlock-bcachefs-custom.service"
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# "x-systemd.after=unlock-bcachefs-custom.service"
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];
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};
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fileSystems."/nix" = {
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device = PRIMARY;
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fsType = "bcachefs";
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options = [
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"X-mount.mkdir"
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"X-mount.subdir=@nix"
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"relatime"
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];
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};
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fileSystems."/.snapshots" = {
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device = PRIMARY;
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fsType = "bcachefs";
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options = [
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"X-mount.mkdir"
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"X-mount.subdir=@snapshots"
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"relatime"
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];
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};
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# (optional) for preservation/impermanence
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fileSystems."/persist" = {
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device = PRIMARY;
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fsType = "bcachefs";
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options = [
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"X-mount.mkdir"
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"X-mount.subdir=@persist"
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];
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};
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}
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# SWAP (optional)
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{ swapDevices = [ { device = SWAP; } ]; }
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# Disable bcachefs built in password prompts for all mounts (which asks for every single subdir mount above
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(
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let
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disableFs = fs: {
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name = "unlock-bcachefs-${utils.escapeSystemdPath fs.mountPoint}";
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value = {
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enable = false;
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};
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};
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in
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{
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boot.initrd.systemd.enable = true;
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# https://github.com/NixOS/nixpkgs/blob/6cdf2f456a57164282ede1c97fc5532d9dba1ee0/nixos/modules/tasks/filesystems/bcachefs.nix#L254-L259
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systemd.services =
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let
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isSystemdNonBootBcache = fs: (fs.fsType == "bcachefs") && (!utils.fsNeededForBoot fs);
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bcacheNonBoots = lib.filterAttrs (k: fs: isSystemdNonBootBcache fs) config.fileSystems;
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in
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(lib.mapAttrs' (k: disableFs) bcacheNonBoots);
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# The above auto generates these...
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# {
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# "unlock-bcachefs-${escapeSystemdPath "/.old_roots"}".enable = false;
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# "unlock-bcachefs-${escapeSystemdPath "/.snapshots"}".enable = false;
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# "unlock-bcachefs-${escapeSystemdPath "/.swap"}".enable = false;
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# "unlock-bcachefs-${escapeSystemdPath "/persist"}".enable = false;
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# };
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# https://github.com/NixOS/nixpkgs/blob/6cdf2f456a57164282ede1c97fc5532d9dba1ee0/nixos/modules/tasks/filesystems/bcachefs.nix#L291
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boot.initrd.systemd.services =
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let
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isSystemdBootBcache = fs: (fs.fsType == "bcachefs") && (utils.fsNeededForBoot fs);
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bcacheBoots = lib.filterAttrs (k: fs: isSystemdBootBcache fs) config.fileSystems;
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in
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(lib.mapAttrs' (k: disableFs) bcacheBoots);
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# same with that above
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# {
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# "unlock-bcachefs-${escapeSystemdPath "/sysroot"}".enable = false;
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# "unlock-bcachefs-${escapeSystemdPath "/"}".enable = false;
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# "unlock-bcachefs-${escapeSystemdPath "/nix"}".enable = false;
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# };
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}
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)
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# Bcachefs auto decryption
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{
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boot.supportedFilesystems = [
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"bcachefs"
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];
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# From a USB key # NOTE this method does work but if you want to boot w/o
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# and get prompted it takes 30 seconds to fail
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# boot.initrd.systemd.mounts = [
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# {
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# what = USB_KEY;
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# type = "bcachefs";
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# where = "/usb_key";
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# options = "ro";
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# description = "key";
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# wantedBy = [
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# "initrd.target"
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# "initrd-root-fs.target"
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# ];
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# }
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# ];
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boot.initrd.systemd.services.unlock-bcachefs-custom = {
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description = "Custom single bcachefs unlock for all subvolumes";
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# Make this part of the root-fs chain, not just initrd.target
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wantedBy = [
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# "initrd.target"
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"sysroot.mount"
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"initrd-root-fs.target"
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];
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before = [
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"sysroot.mount"
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"initrd-root-fs.target"
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];
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after = [
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# "usb_key.mount"
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"initrd-root-device.target"
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];
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requires = [
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"initrd-root-device.target"
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primaryDeviceUnit
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];
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# unitConfig = {
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# # Ensure this service doesn't time out if USB detection takes a while
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# DefaultDependencies = "no";
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# };
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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KeyringMode = "shared"; # TODO so it shares with reset root below, not needed otherwise
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};
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# script = ''
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# echo "Using USB key for bcachefs unlock: ${USB_KEY}"
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#
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# # only try mount if the node exists
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# if [ ! -e "${USB_KEY}" ]; then
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# echo "USB key device ${USB_KEY} not present in initrd"
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# exit 1
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# fi
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#
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# ${pkgs.bcachefs-tools}/bin/bcachefs unlock -f /usb_key/key "${PRIMARY}"
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# echo "bcachefs unlock successful for ${PRIMARY}"
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# '';
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script = ''
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echo "Searching for USB Unlock Key..."
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KEY_FOUND=0
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# 4 second search
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for i in {1..40}; do
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if [ -e "${USB_KEY}" ]; then
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KEY_FOUND=1
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break
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fi
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sleep 0.1
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done
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if [ "$KEY_FOUND" -eq 1 ]; then
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echo "USB Key found at ${USB_KEY}. Attempting unlock..."
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mkdir -p /tmp/usb_key_mount
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# Mount read-only
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if mount -t bcachefs -o ro "${USB_KEY}" /tmp/usb_key_mount; then
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# Attempt unlock
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${pkgs.bcachefs-tools}/bin/bcachefs unlock -f /tmp/usb_key_mount/key "${PRIMARY}"
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UNLOCK_STATUS=$?
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# Cleanup
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umount /tmp/usb_key_mount
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if [ $UNLOCK_STATUS -eq 0 ]; then
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echo "Bcachefs unlock successful!"
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exit 0
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else
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echo "Failed to unlock with USB key."
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fi
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else
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echo "Failed to mount USB key device."
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fi
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else
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echo "USB Key not found within timeout."
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fi
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# 3. Fallback
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echo "Proceeding to standard mount (password prompt will appear if still locked)..."
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exit 0
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'';
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};
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# TODO rotate root
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}
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# Reset root for erase your darlings/impermanence/preservation
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(lib.mkIf false {
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boot.initrd.systemd.services.bcachefs-reset-root = {
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description = "Reset bcachefs root subvolume before pivot";
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# We want this to run after we've ATTEMPTED to unlock,
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# but strictly BEFORE the real root is mounted at /sysroot
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after = [
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"initrd-root-device.target"
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"cryptsetup.target"
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"unlock-bcachefs-custom.service"
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];
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# This is the most important part: prevent sysroot from mounting until we are done resetting it
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before = [
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"sysroot.mount"
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];
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requires = [
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primaryDeviceUnit
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"unlock-bcachefs-custom.service"
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];
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wantedBy = [
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"initrd-root-fs.target"
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"sysroot.mount"
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"initrd.target"
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];
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serviceConfig = {
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Type = "oneshot";
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KeyringMode = "shared";
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Environment = "PATH=${
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lib.makeBinPath [
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pkgs.coreutils
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pkgs.util-linux
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pkgs.findutils
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pkgs.gawk
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pkgs.bcachefs-tools
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]
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}:/bin:/sbin";
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};
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script = ''
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# 1. Enable Debugging
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set -x
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echo $PATH
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# 2. Define Cleanup Trap (Robust)
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cleanup() {
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# If the script failed before creating the new root, make sure we create it
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if [[ ! -e /primary_tmp/@root ]]; then
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echo "Cleanup: Creating new @root"
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bcachefs subvolume create /primary_tmp/@root
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fi
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# Robust replacement for 'mountpoint -q'
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if ls /primary_tmp; then
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echo "Cleanup: Unmounting /primary_tmp"
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umount /primary_tmp
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fi
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}
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trap cleanup EXIT
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mkdir -p /primary_tmp
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# If unlocked, mounts instantly. If locked, prompts for password on TTY.
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echo "Mounting ${PRIMARY}..."
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if ! mount "${PRIMARY}" /primary_tmp; then
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echo "Mount failed. Cannot reset root."
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exit 1
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fi
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# 5. Snapshot & Prune Logic
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if [[ -e /primary_tmp/@root ]]; then
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mkdir -p /primary_tmp/@snapshots/old_roots
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# Use safe timestamp format (dashes instead of colons)
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timestamp=$(date --date="@$(stat -c %Y /primary_tmp/@root)" "+%Y-%m-%d_%H-%M-%S")
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echo "Snapshotting @root to .../$timestamp"
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bcachefs subvolume snapshot /primary_tmp/@root "/primary_tmp/@snapshots/old_roots/$timestamp"
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echo "Deleting current @root"
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bcachefs subvolume delete /primary_tmp/@root
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# --- PRUNING LOGIC ---
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echo "Pruning snapshots..."
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# Get list of snapshots sorted by name (which effectively sorts by date: YYYY-MM-DD...)
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# ls -r puts newest first
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snapshots=$(ls -1Ar /primary_tmp/@snapshots/old_roots)
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declare -A kept_weeks
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declare -A kept_months
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processed_count=0
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for snap in $snapshots; do
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keep=false
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# Parse date from filename (Replace _ with space for date command)
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date_str=$(echo "$snap" | sed 's/_/ /')
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# Get metadata
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ts=$(date -d "$date_str" +%s)
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week_id=$(date -d "$date_str" +%Y-W%U)
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month_id=$(date -d "$date_str" +%Y-%m)
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now=$(date +%s)
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days_old=$(( (now - ts) / 86400 ))
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# RULE 1: Keep 5 most recent (Always)
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if [ $processed_count -lt 5 ]; then
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keep=true
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fi
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# RULE 2: Weekly for last month (Age < 32 days)
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# "at least 1 root from each week from the last month"
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if [ $days_old -le 32 ]; then
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if [ -z "''${kept_weeks[$week_id]}" ]; then
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keep=true
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kept_weeks[$week_id]=1
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fi
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fi
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# RULE 3: Monthly for older snapshots
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# "at least 1 root from a month ago" (implies monthly retention indefinitely)
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if [ $days_old -gt 32 ]; then
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if [ -z "''${kept_months[$month_id]}" ]; then
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keep=true
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kept_months[$month_id]=1
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fi
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fi
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if [ "$keep" = true ]; then
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echo "Keeping: $snap"
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else
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echo "Deleting: $snap"
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bcachefs subvolume delete "/primary_tmp/@snapshots/old_roots/$snap"
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fi
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processed_count=$((processed_count + 1))
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done
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fi
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# Trap handles creating new root and unmount
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'';
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};
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})
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]
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