monitoring: add grafana annotations for zfs scrub events

services/zfs-scrub-annotations.nix

@@ -0,0 +1,36 @@
+{
+  config,
+  pkgs,
+  service_configs,
+  lib,
+  ...
+}:
+let
+  grafanaUrl = "http://127.0.0.1:${toString service_configs.ports.private.grafana.port}";
+
+  script = pkgs.writeShellApplication {
+    name = "zfs-scrub-annotations";
+    runtimeInputs = with pkgs; [
+      curl
+      jq
+      coreutils
+      gnugrep
+      gnused
+      config.boot.zfs.package
+    ];
+    text = builtins.readFile ./zfs-scrub-annotations.sh;
+  };
+in
+{
+  systemd.services.zfs-scrub = {
+    environment = {
+      GRAFANA_URL = grafanaUrl;
+      STATE_DIR = "/run/zfs-scrub-annotations";
+    };
+    serviceConfig = {
+      RuntimeDirectory = "zfs-scrub-annotations";
+      ExecStartPre = [ "-${lib.getExe script} start" ];
+      ExecStopPost = [ "${lib.getExe script} stop" ];
+    };
+  };
+}