feat(ward): local snapshotting via zrepl

hosts/ward/fs.nix

@@ -32,5 +32,70 @@
     };
   };
 
+  services.zrepl = {
+    enable = true;
+    settings = {
+      global = {
+        logging = [
+          {
+            type = "syslog";
+            level = "info";
+            format = "human";
+          }
+        ];
+        # TODO zrepl monitor
+        #monitoring = [
+        #  {
+        #    type = "prometheus";
+        #    listen = ":9811";
+        #    listen_freebind = true;
+        #  }
+        #];
+      };
+
+      jobs = [
+        {
+          name = "local-snapshots";
+          type = "snap";
+          filesystems = {
+            "rpool/local/state<" = true;
+            "rpool/safe<" = true;
+          };
+          snapshotting = {
+            type = "periodic";
+            prefix = "zrepl-";
+            timestamp_format = "iso-8601";
+            interval = "15m";
+          };
+          pruning.keep = [
+            # Keep all manual snapshots
+            {
+              type = "regex";
+              regex = "^zrepl-.*$";
+              negate = true;
+            }
+            # Keep last n snapshots
+            {
+              type = "last_n";
+              regex = "^zrepl-.*$";
+              count = 10;
+            }
+            # Prune periodically
+            {
+              type = "grid";
+              regex = "^zrepl-.*$";
+              grid = lib.concatStringsSep " | " [
+                "72x1h"
+                "90x1d"
+                "60x1w"
+                "24x30d"
+              ];
+            }
+          ];
+        }
+      ];
+    };
+  };
+
   boot.initrd.luks.devices.enc-rpool.allowDiscards = true;
 }