Merge pull request #113370 from chkno/prometheus-systemd-exporter-no-flags

prometheus-systemd-exporter: Init at 0.4.0

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

@@ -53,6 +53,7 @@ let
     "smokeping"
     "sql"
     "surfboard"
+    "systemd"
     "tor"
     "unifi"
     "unifi-poller"

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

@@ -0,0 +1,18 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let cfg = config.services.prometheus.exporters.systemd;
+
+in {
+  port = 9558;
+
+  serviceOpts = {
+    serviceConfig = {
+      ExecStart = ''
+        ${pkgs.prometheus-systemd-exporter}/bin/systemd_exporter \
+          --web.listen-address ${cfg.listenAddress}:${toString cfg.port}
+      '';
+    };
+  };
+}

nixos/tests/prometheus-exporters.nix

@@ -835,6 +835,22 @@ let
       '';
     };
 
+    systemd = {
+      exporterConfig = {
+        enable = true;
+      };
+      metricProvider = { };
+      exporterTest = ''
+        wait_for_unit("prometheus-systemd-exporter.service")
+        wait_for_open_port(9558)
+        succeed(
+            "curl -sSf localhost:9558/metrics | grep -q '{}'".format(
+                'systemd_unit_state{name="basic.target",state="active",type="target"} 1'
+            )
+        )
+      '';
+    };
+
     tor = {
       exporterConfig = {
         enable = true;