1 files changed, 20 insertions, 1 deletions
diff --git a/nixos/modules/services/misc/snapper.nix b/nixos/modules/services/misc/snapper.nix
index 3a3ed1b5c0f56..a42fca5b60289 100644
--- a/nixos/modules/services/misc/snapper.nix
+++ b/nixos/modules/services/misc/snapper.nix
@@ -103,6 +103,18 @@ in
       '';
     };
 
+    persistentTimer = mkOption {
+      default = false;
+      type = types.bool;
+      example = true;
+      description = ''
+        Set the `Persistent` option for the
+        {manpage}`systemd.timer(5)`
+        which triggers the snapshot immediately if the last trigger
+        was missed (e.g. if the system was powered down).
+      '';
+    };
+
     cleanupInterval = mkOption {
       type = types.str;
       default = "1d";
@@ -198,7 +210,14 @@ in
       inherit documentation;
       requires = [ "local-fs.target" ];
       serviceConfig.ExecStart = "${pkgs.snapper}/lib/snapper/systemd-helper --timeline";
-      startAt = cfg.snapshotInterval;
+    };
+
+    systemd.timers.snapper-timeline = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        Persistent = cfg.persistentTimer;
+        OnCalendar = cfg.snapshotInterval;
+      };
     };
 
     systemd.services.snapper-cleanup = {