prometheus-tor-exporter: init at 0.3

Upstream: https://github.com/atx/prometheus-tor_exporter

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

@@ -30,6 +30,7 @@ let
     postfix   = import ./exporters/postfix.nix   { inherit config lib pkgs; };
     snmp      = import ./exporters/snmp.nix      { inherit config lib pkgs; };
     surfboard = import ./exporters/surfboard.nix { inherit config lib pkgs; };
+    tor       = import ./exporters/tor.nix       { inherit config lib pkgs; };
     unifi     = import ./exporters/unifi.nix     { inherit config lib pkgs; };
     varnish   = import ./exporters/varnish.nix   { inherit config lib pkgs; };
   };

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

@@ -0,0 +1,40 @@
+{ config, lib, pkgs }:
+
+with lib;
+
+let
+  cfg = config.services.prometheus.exporters.tor;
+in
+{
+  port = 9130;
+  extraOpts = {
+    torControlAddress = mkOption {
+      type = types.str;
+      default = "127.0.0.1";
+      description = ''
+        Tor control IP address or hostname.
+      '';
+    };
+
+    torControlPort = mkOption {
+      type = types.int;
+      default = 9051;
+      description = ''
+        Tor control port.
+      '';
+    };
+  };
+  serviceOpts = {
+    serviceConfig = {
+      DynamicUser = true;
+      ExecStart = ''
+        ${pkgs.prometheus-tor-exporter}/bin/prometheus-tor-exporter \
+          -b ${cfg.listenAddress} \
+          -p ${toString cfg.port} \
+          -a ${cfg.torControlAddress} \
+          -c ${toString cfg.torControlPort} \
+          ${concatStringsSep " \\\n  " cfg.extraFlags}
+      '';
+    };
+  };
+}