1 files changed, 52 insertions, 0 deletions

diff --git a/modules/borgbackup/btrfs-snapshots.nix b/modules/borgbackup/btrfs-snapshots.nix
new file mode 100644
index 00000000..96d2b2ba
--- /dev/null
+++ b/modules/borgbackup/btrfs-snapshots.nix
@@ -0,0 +1,52 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.btrfs-snapshots;
+
+  snapshotMount = str: "${str}${cfg.mountSuffix}";
+in {
+  options = {
+
+    services.btrfs-snapshots = {
+      enable = mkEnableOption "a systemd unit for btrfs snapshots";   
+
+      mountSuffix = mkOption {
+        type = types.str;
+        default = ".snapshot";
+      };
+
+      readOnly = mkOption {
+        type = types.bool;
+        default = true;
+      };
+
+      persist = mkOption {
+        type = types.bool;
+        default = false;
+      };
+    };
+
+  };
+
+  
+  config = mkIf cfg.enable {
+    systemd.services."btrfs-snapshot@" = {
+      enable = true;
+
+      unitConfig = {
+        StopWhenUnneeded = !cfg.persist;
+      };
+
+      serviceConfig = with pkgs; {
+        Type = "oneshot";
+        ExecStartPre = "-${btrfs-progs}/bin/btrfs subvolume delete -c ${snapshotMount "%f"}";
+        ExecStart = "${btrfs-progs}/bin/btrfs subvolume snapshot ${optionalString cfg.readOnly "-r"} %f ${snapshotMount "%f"}";
+        RemainAfterExit = true;
+        ExecStop = "${btrfs-progs}/bin/btrfs subvolume delete -c ${snapshotMount "%f"}";
+      };
+    };
+
+  };
+}