node线上项目连接mysql出现 504 Gateway Time-Out

var connection = mysql.createConnection({     
  host     : 'localhost',       
  user     : 'root',              
  password : '123456',       
  port: '3306',                   
  database: 'test' 
});

一定别忘了加端口号 ↓

port: '3306',