Merge pull request #146653 from DarkDNA/nixos/fix-systemd-exporter/extraFlags

nixos/prometheus/systemd: Implement the extraFlags config option.

nixos/modules/services/monitoring/prometheus/exporters/systemd.nix

@@ -11,7 +11,7 @@ in {
     serviceConfig = {
       ExecStart = ''
         ${pkgs.prometheus-systemd-exporter}/bin/systemd_exporter \
-          --web.listen-address ${cfg.listenAddress}:${toString cfg.port}
+          --web.listen-address ${cfg.listenAddress}:${toString cfg.port} ${concatStringsSep " " cfg.extraFlags}
       '';
       RestrictAddressFamilies = [
         # Need AF_UNIX to collect data

nixos/tests/prometheus-exporters.nix

@@ -1156,6 +1156,10 @@ let
     systemd = {
       exporterConfig = {
         enable = true;
+
+        extraFlags = [
+          "--collector.enable-restart-count"
+        ];
       };
       metricProvider = { };
       exporterTest = ''
@@ -1166,6 +1170,11 @@ let
                 'systemd_unit_state{name="basic.target",state="active",type="target"} 1'
             )
         )
+        succeed(
+            "curl -sSf localhost:9558/metrics | grep '{}'".format(
+                'systemd_service_restart_total{state="prometheus-systemd-exporter.service"} 0'
+            )
+        )
       '';
     };