logstash service improvements

* add logstash-contrib plugins package
* add additional options to the logstash service

nixos/modules/services/logging/logstash.nix

@@ -4,6 +4,9 @@ with lib;
 
 let
   cfg = config.services.logstash;
+  pluginPath = lib.concatStringsSep ":" cfg.plugins;
+  havePluginPath = lib.length cfg.plugins > 0;
+  ops = lib.optionalString;
 
 in
 
@@ -20,12 +23,50 @@ in
         description = "Enable logstash.";
       };
 
+      package = mkOption {
+        type = types.package;
+        default = pkgs.logstash;
+        example = literalExample "pkgs.logstash";
+        description = "Logstash package to use.";
+      };
+
+      plugins = mkOption {
+        type = types.listOf types.path;
+        default = [ ];
+        example = literalExample "[ pkgs.logstash-contrib ]";
+        description = "The paths to find other logstash plugins in.";
+      };
+
+      watchdogTimeout = mkOption {
+        type = types.int;
+        default = 10;
+        description = "Set watchdog timeout value in seconds.";
+      };
+
+      filterWorkers = mkOption {
+        type = types.int;
+        default = 1;
+        description = "The quantity of filter workers to run.";
+      };
+
       enableWeb = mkOption {
         type = types.bool;
         default = false;
         description = "Enable the logstash web interface.";
       };
 
+      address = mkOption {
+        type = types.str;
+        default = "0.0.0.0";
+        description = "Address on which to start webserver.";
+      };
+
+      port = mkOption {
+        type = types.str;
+        default = "9292";
+        description = "Port on which to start webserver.";
+      };
+
       inputConfig = mkOption {
         type = types.lines;
         default = ''stdin { type => "example" }'';
@@ -79,19 +120,25 @@ in
       wantedBy = [ "multi-user.target" ];
       environment = { JAVA_HOME = jre; };
       serviceConfig = {
-        ExecStart = "${logstash}/bin/logstash agent -f ${writeText "logstash.conf" ''
-          input {
-            ${cfg.inputConfig}
-          }
+        ExecStart =
+          "${cfg.package}/bin/logstash agent " +
+          "-w ${toString cfg.filterWorkers} " +
+          ops havePluginPath "--pluginpath ${pluginPath} " +
+          "--watchdog-timeout ${toString cfg.watchdogTimeout} " +
+          "-f ${writeText "logstash.conf" ''
+            input {
+              ${cfg.inputConfig}
+            }
 
-          filter {
-            ${cfg.filterConfig}
-          }
+            filter {
+              ${cfg.filterConfig}
+            }
 
-          output {
-            ${cfg.outputConfig}
-          }
-        ''} ${optionalString cfg.enableWeb "-- web"}";
+            output {
+              ${cfg.outputConfig}
+            }
+          ''} " +
+          ops cfg.enableWeb "-- web -a ${cfg.address} -p ${cfg.port}";
       };
     };
   };