memcached: Add more options and extraOptions support

modules/services/databases/memcached.nix

@@ -30,6 +30,36 @@ in
         description = "The user to run Memcached as";
       };
 
+      listen = mkOption {
+        default = "127.0.0.1";
+        description = "The IP address to bind to";
+      };
+
+      port = mkOption {
+        default = 11211;
+        description = "The port to bind to";
+      };
+
+      socket = mkOption {
+        default = "";
+        description = "Unix socket path to listen on. Setting this will disable network support";
+        example = "/var/run/memcached";
+      };
+
+      maxMemory = mkOption {
+        default = 64;
+        description = "The maximum amount of memory to use for storage, in megabytes.";
+      };
+
+      maxConnections = mkOption {
+        default = 1024;
+        description = "The maximum number of simultaneous connections";
+      };
+
+      extraOptions = mkOption {
+        default = [];
+        description = "A list of extra options that will be added as a suffix when running memcached";
+      };
     };
 
   };
@@ -52,7 +82,13 @@ in
         after = [ "network.target" ];
 
         serviceConfig = {
-          ExecStart = "${memcached}/bin/memcached";
+          ExecStart =
+            let
+              networking = if cfg.socket != ""
+                then "-s ${cfg.socket}"
+                else "-l ${cfg.listen} -p ${toString cfg.port}";
+            in "${memcached}/bin/memcached ${networking} -m ${toString cfg.maxMemory} -c ${toString cfg.maxConnections} ${concatStringsSep " " cfg.extraOptions}";
+
           User = cfg.user;
         };
       };