code: function(callback)
      {
          self.pool = (require('mysql')).createPool({
              user     : self.config.username,
              password : self.config.password,
              database : self.config.db,
              host     : self.config.host,
              port     : self.config.port
          });
  
          // Initiate a connection - just to proof configuration
          self.pool.getConnection(function(err, connection) {
  
              if (err || !connection) {
                  callback && callback(err);
                  return;
              }
  
              self.prepare(connection);
  
              // The connection can be closed immediately
              connection.release();
              return callback && callback(null, self.pool);
          });
      }
docs: Setup the plain MySQL connection, pooling enabled