prometheus-wireguard-exporter: init at 2.0.1

This is a simple exporter which exports the information
provided by `wg show all dump` to prometheus.

Co-authored-by: Franz Pletz <fpletz@fnordicwalking.de>

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

@@ -34,6 +34,7 @@ let
     unifi     = import ./exporters/unifi.nix     { inherit config lib pkgs; };
     varnish   = import ./exporters/varnish.nix   { inherit config lib pkgs; };
     bind      = import ./exporters/bind.nix      { inherit config lib pkgs; };
+    wireguard = import ./exporters/wireguard.nix { inherit config lib pkgs; };
   };
 
   mkExporterOpts = ({ name, port }: {

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

@@ -0,0 +1,42 @@
+{ config, lib, pkgs }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.wireguard;
+in {
+  port = 9586;
+  extraOpts = {
+    verbose = mkEnableOption "Verbose logging mode for prometheus-wireguard-exporter";
+
+    wireguardConfig = mkOption {
+      type = with types; nullOr (either path str);
+      default = null;
+
+      description = ''
+        Path to the Wireguard Config to
+        <link xlink:href="https://github.com/MindFlavor/prometheus_wireguard_exporter/tree/2.0.0#usage">add the peer's name to the stats of a peer</link>.
+
+        Please note that <literal>networking.wg-quick</literal> is required for this feature
+        as <literal>networking.wireguard</literal> uses
+        <citerefentry><refentrytitle>wg</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        to set the peers up.
+      '';
+    };
+  };
+  serviceOpts = {
+    script = ''
+      ${pkgs.prometheus-wireguard-exporter}/bin/prometheus_wireguard_exporter \
+        -p ${toString cfg.port} \
+        ${optionalString cfg.verbose "-v"} \
+        ${optionalString (cfg.wireguardConfig != null) "-n ${cfg.wireguardConfig}"}
+    '';
+
+    path = [ pkgs.wireguard-tools ];
+
+    serviceConfig = {
+      DynamicUser = true;
+      AmbientCapabilities = [ "CAP_NET_ADMIN" ];
+    };
+  };
+}