nixos/prometheus-exporters: Added kafka exporter

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

@@ -79,6 +79,7 @@ let
         "jitsi"
         "json"
         "junos-czerwonk"
+        "kafka"
         "kea"
         "keylight"
         "klipper"

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

@@ -0,0 +1,45 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.services.prometheus.exporters.kafka;
+  inherit (lib)
+    mkIf
+    mkOption
+    mkMerge
+    types
+    concatStringsSep
+    ;
+in {
+  port = 8080;
+
+  extraOpts = {
+    package = lib.mkPackageOption pkgs "kminion" { };
+
+    environmentFile = mkOption {
+      type = with types; nullOr path;
+      default = null;
+      description = ''
+        File containing the credentials to access the repository, in the
+        format of an EnvironmentFile as described by systemd.exec(5)
+      '';
+    };
+  };
+  serviceOpts = mkMerge ([{
+    serviceConfig = {
+      ExecStart = ''
+        ${lib.getExe cfg.package}
+      '';
+      EnvironmentFile = mkIf (cfg.environmentFile != null) cfg.environmentFile;
+      RestartSec = "5s";
+      RestrictAddressFamilies = [
+        "AF_INET"
+        "AF_INET6"
+      ];
+    };
+  }] ++ [
+    (mkIf config.services.apache-kafka.enable {
+      after = [ "apache-kafka.service" ];
+      requires = [ "apache-kafka.service" ];
+    })
+  ]);
+}