nixos/tests: add grafana test (#29531)

nixos/release.nix

···
   tests.gocd-server = callTest tests/gocd-server.nix {};
   tests.gnome3 = callTest tests/gnome3.nix {};
   tests.gnome3-gdm = callTest tests/gnome3-gdm.nix {};
+  tests.grafama = callTest tests/grafana.nix {};
   tests.hardened = callTest tests/hardened.nix { };
   tests.hibernate = callTest tests/hibernate.nix {};
   tests.hound = callTest tests/hound.nix {};

nixos/tests/grafana.nix

···
+import ./make-test.nix ({ lib, ... }:
+{
+  name = "grafana";
+
+  meta = with lib.maintainers; {
+    maintainers = [ willibutz ];
+  };
+
+  machine = { config, pkgs, ... }: {
+    services.grafana = {
+      enable = true;
+      addr = "localhost";
+      analytics.reporting.enable = false;
+      domain = "localhost";
+      security.adminUser = "testusername";
+    };
+  };
+
+  testScript = ''
+    $machine->start;
+    $machine->waitForUnit("grafana.service");
+    $machine->waitForOpenPort(3000);
+    $machine->succeed("curl -sS http://127.0.0.1:3000/");
+  '';
+})