问题描述：
我使用sequalize orm和firebase cloud函数，每当我查询mysql db时，都会出现sequelizeconnectioneror:connect etimedout错误。当函数通过firebase cli在localhost上运行时，它可以正常工作。下面是sequalize连接方法。
代码段

var sequelize = new Sequelize('dbname, 'username', 'password', {
host: "host",
dialect: 'mysql',
define: {
    paranoid: true
},
pool: {
    max: 5,
    min: 0,
    acquire: 30000,
    idle: 1
},
operatorsAliases: false})

当函数在端口5000上通过firebase cli本地运行时，上面的代码工作得非常好。当我在firebase上部署它并运行相同的函数时，我得到以下错误。

2018-06-23T11:31:53.887Z E app: Unhandled rejection
2018-06-23T11:31:55.187Z E app: SequelizeConnectionError: connect ETIMEDOUT
    at Utils.Promise.tap.then.catch.err (/user_code/node_modules/sequelize/lib/dialects/mysql/connection-manager.js:149:19)
    at tryCatcher (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:569:18)
    at Promise._settlePromise0 (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:689:18)
    at Async._drainQueue (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues (/user_code/node_modules/sequelize/node_modules/bluebird/js/release/async.js:17:14
)