nixos/telegraf: add test

nixos/tests/all-tests.nix

@@ -200,6 +200,7 @@ in
   syncthing-relay = handleTest ./syncthing-relay.nix {};
   systemd = handleTest ./systemd.nix {};
   taskserver = handleTest ./taskserver.nix {};
+  telegraf = handleTest ./telegraf.nix {};
   tomcat = handleTest ./tomcat.nix {};
   tor = handleTest ./tor.nix {};
   transmission = handleTest ./transmission.nix {};

nixos/tests/telegraf.nix

@@ -0,0 +1,30 @@
+import ./make-test.nix ({ pkgs, ...} : {
+  name = "telegraf";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ mic92 ];
+  };
+
+  machine = { ... }: {
+    services.telegraf.enable = true;
+    services.telegraf.extraConfig = {
+      agent.interval = "1s";
+      agent.flush_interval = "1s";
+      inputs.exec = {
+        commands = [
+          "${pkgs.runtimeShell} -c 'echo example,tag=a i=42i'"
+        ];
+        timeout = "5s";
+        data_format = "influx";
+      };
+      outputs.file.files = ["/tmp/metrics.out"];
+      outputs.file.data_format = "influx";
+    };
+  };
+
+  testScript = ''
+    startAll;
+
+    $machine->waitForUnit("telegraf.service");
+    $machine->waitUntilSucceeds("grep -q example /tmp/metrics.out");
+  '';
+})