nixos/collectd: add nixos test

nixos/tests/all-tests.nix

@@ -70,6 +70,7 @@ in
   cloud-init = handleTest ./cloud-init.nix {};
   cntr = handleTest ./cntr.nix {};
   cockroachdb = handleTestOn ["x86_64-linux"] ./cockroachdb.nix {};
+  collectd = handleTest ./collectd.nix {};
   consul = handleTest ./consul.nix {};
   containers-bridge = handleTest ./containers-bridge.nix {};
   containers-custom-pkgs.nix = handleTest ./containers-custom-pkgs.nix {};

nixos/tests/collectd.nix

@@ -0,0 +1,33 @@
+import ./make-test-python.nix ({ pkgs, ... }: {
+  name = "collectd";
+  meta = { };
+
+  machine =
+    { pkgs, ... }:
+
+    {
+      services.collectd = {
+        enable = true;
+        plugins = {
+          rrdtool = ''
+            DataDir "/var/lib/collectd/rrd"
+          '';
+          load = "";
+        };
+      };
+      environment.systemPackages = [ pkgs.rrdtool ];
+    };
+
+  testScript = ''
+    machine.wait_for_unit("collectd.service")
+    hostname = machine.succeed("hostname").strip()
+    file = f"/var/lib/collectd/rrd/{hostname}/load/load.rrd"
+    machine.wait_for_file(file);
+    machine.succeed(f"rrdinfo {file} | logger")
+    # check that this file contains a shortterm metric
+    machine.succeed(f"rrdinfo {file} | grep -F 'ds[shortterm].min = '")
+    # check that there are frequent updates
+    machine.succeed(f"cp {file} before")
+    machine.wait_until_fails(f"cmp before {file}")
+  '';
+})

pkgs/tools/system/collectd/default.nix

@@ -2,6 +2,7 @@
 , autoreconfHook
 , pkg-config
 , libtool
+, nixosTests
 , ...
 }@args:
 let
@@ -41,6 +42,10 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
+  passthru.tests = {
+    inherit (nixosTests) collectd;
+  };
+
   meta = with lib; {
     description = "Daemon which collects system performance statistics periodically";
     homepage = "https://collectd.org";