nixos/mysql: minor cleanup and formatting

nixos/modules/services/databases/mysql.nix

@@ -62,7 +62,7 @@ in
           Group account under which MySQL runs.
 
           <note><para>
-          If left as the default value this user will automatically be created
+          If left as the default value this group will automatically be created
           on system activation, otherwise you are responsible for
           ensuring the user exists before the MySQL service starts.
           </para></note>
@@ -283,7 +283,7 @@ in
         };
 
         masterPort = mkOption {
-          type = types.int;
+          type = types.port;
           default = 3306;
           description = "Port number on which the MySQL master server runs.";
         };
@@ -295,7 +295,7 @@ in
 
   ###### implementation
 
-  config = mkIf config.services.mysql.enable {
+  config = mkIf cfg.enable {
 
     services.mysql.dataDir =
       mkDefault (if versionAtLeast config.system.stateVersion "17.09" then "/var/lib/mysql"
@@ -334,16 +334,14 @@ in
 
     environment.etc."my.cnf".source = cfg.configFile;
 
-    systemd.services.mysql = let
-      hasNotify = isMariaDB;
-    in {
+    systemd.services.mysql = {
       description = "MySQL Server";
 
       after = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
       restartTriggers = [ cfg.configFile ];
 
-        unitConfig.RequiresMountsFor = "${cfg.dataDir}";
+      unitConfig.RequiresMountsFor = cfg.dataDir;
 
       path = [
         # Needed for the mysql_install_db command in the preStart script
@@ -379,7 +377,7 @@ in
         # The super user account to use on *first* run of MySQL server
         superUser = if isMariaDB then cfg.user else "root";
       in ''
-          ${optionalString (!hasNotify) ''
+        ${optionalString (!isMariaDB) ''
           # Wait until the MySQL server is available for use
           count=0
           while [ ! -e /run/mysqld/mysqld.sock ]
@@ -479,7 +477,7 @@ in
 
       serviceConfig = mkMerge [
         {
-            Type = if hasNotify then "notify" else "simple";
+          Type = if isMariaDB then "notify" else "simple";
           Restart = "on-abort";
           RestartSec = "5s";
 
@@ -519,7 +517,5 @@ in
         })
       ];
     };
-
   };
-
 }