问{错误: connect ETIMEDOUT at Connection._handleConnectTimeout and wierd undefined message

EN

{ Error: connect ETIMEDOUT
    at Connection._handleConnectTimeout (/srv/node_modules/mysql/lib/Connection.js:409:13)
    at Object.onceWrapper (events.js:313:30)
    at emitNone (events.js:106:13)
    at Socket.emit (events.js:208:7)
    at Socket._onTimeout (net.js:422:8)
    at ontimeout (timers.js:498:11)
    at tryOnTimeout (timers.js:323:5)
    at Timer.listOnTimeout (timers.js:290:5)
    --------------------
    at Protocol._enqueue (/srv/node_modules/mysql/lib/protocol/Protocol.js:144:48)
    at Protocol.handshake (/srv/node_modules/mysql/lib/protocol/Protocol.js:51:23)
    at Connection.connect (/srv/node_modules/mysql/lib/Connection.js:116:18)
    at Promise (/srv/index.js:34:19)
    at new Promise (<anonymous>)
    at connectToDatabase (/srv/index.js:33:12)
    at handleReadFromMySQL (/srv/index.js:52:12)
    at WebhookClient.handleRequest (/srv/node_modules/dialogflow-fulfillment/src/dialogflow-fulfillment.js:303:44)
    at exports.dialogflowFirebaseFulfillment.functions.https.onRequest (/srv/index.js:104:9)
    at cloudFunction (/srv/node_modules/firebase-functions/lib/providers/https.js:57:9)
  errorno: 'ETIMEDOUT',
  code: 'ETIMEDOUT',
  syscall: 'connect',
  fatal: true }

// See https://github.com/dialogflow/dialogflow-fulfillment-nodejs
// for Dialogflow fulfillment library docs, samples, and to report issues
'use strict';

const functions = require('firebase-functions');
const {WebhookClient} = require('dialogflow-fulfillment');
const {Card, Suggestion} = require('dialogflow-fulfillment');
const mysql = require('mysql');

process.env.DEBUG = 'dialogflow:debug'; // enables lib debugging statements

exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
  const agent = new WebhookClient({ request, response });
  console.log('Dialogflow Request headers: ' + JSON.stringify(request.headers));
  console.log('Dialogflow Request body: ' + JSON.stringify(request.body));

  function welcome(agent) {
    agent.add(`Welcome to my agent!`);
  }

  function fallback(agent) {
    agent.add(`I didn't understand`);
    agent.add(`I'm sorry, can you try again?`);
  }

function connectToDatabase(){
    const connection = mysql.createConnection({
      host     : '34.93.236.175',
      user     : 'root',
      password : '',
      database : 'django_db',
    });
    return new Promise((resolve,reject) => {
       connection.connect();
       resolve(connection);
    });
  }

  function queryDatabase(connection) {
    return new Promise((resolve,reject) => {
      connection.query('SELECT * from web_user',(error, results, fields) => {
        console.log("result console");
        console.log(results);
        console.log(fields);
        console.log(error);
        resolve(results);
      });
    });
  }

 function handleReadFromMySQL(agent){
    return connectToDatabase()
    .then(connection => {
      return queryDatabase(connection)
      .then(result => {
        console.log(result);
        connection.end();
      }).catch(error => {
        console.log("error");
        console.log(error);
        connection.end();
      });
    }).catch(error=>{
      console.log(error);
    });

 }
  // // Uncomment and edit to make your own intent handler
  // // uncomment `intentMap.set('your intent name here', yourFunctionHandler);`
  // // below to get this function to be run when a Dialogflow intent is matched
  // function yourFunctionHandler(agent) {
  //   agent.add(`This message is from Dialogflow's Cloud Functions for Firebase editor!`);
  //   agent.add(new Card({
  //       title: `Title: this is a card title`,
  //       imageUrl: 'https://developers.google.com/actions/images/badges/XPM_BADGING_GoogleAssistant_VER.png',
  //       text: `This is the body text of a card.  You can even use line\n  breaks and emoji! `,
  //       buttonText: 'This is a button',
  //       buttonUrl: 'https://assistant.google.com/'
  //     })
  //   );
  //   agent.add(new Suggestion(`Quick Reply`));
  //   agent.add(new Suggestion(`Suggestion`));
  //   agent.setContext({ name: 'weather', lifespan: 2, parameters: { city: 'Rome' }});
  // }

  // // Uncomment and edit to make your own Google Assistant intent handler
  // // uncomment `intentMap.set('your intent name here', googleAssistantHandler);`
  // // below to get this function to be run when a Dialogflow intent is matched
  // function googleAssistantHandler(agent) {
  //   let conv = agent.conv(); // Get Actions on Google library conv instance
  //   conv.ask('Hello from the Actions on Google client library!') // Use Actions on Google library
  //   agent.add(conv); // Add Actions on Google library responses to your agent's response
  // }
  // // See https://github.com/dialogflow/fulfillment-actions-library-nodejs
  // // for a complete Dialogflow fulfillment library Actions on Google client library v2 integration sample

  // Run the proper function handler based on the matched Dialogflow intent name
  let intentMap = new Map();
  intentMap.set('Default Welcome Intent', welcome);
  intentMap.set('Default Fallback Intent', fallback);
  intentMap.set('getDataFromMySQL', handleReadFromMySQL);
  // intentMap.set('your intent name here', yourFunctionHandler);
  // intentMap.set('your intent name here', googleAssistantHandler);
  agent.handleRequest(intentMap);
});

{
  "name": "dialogflowFirebaseFulfillment",
  "description": "This is the default fulfillment for a Dialogflow agents using Cloud Functions for Firebase",
  "version": "0.0.1",
  "private": true,
  "license": "Apache Version 2.0",
  "author": "Google Inc.",
  "engines": {
    "node": "8"
  },
  "scripts": {
    "start": "firebase serve --only functions:dialogflowFirebaseFulfillment",
    "deploy": "firebase deploy --only functions:dialogflowFirebaseFulfillment"
  },
  "dependencies": {
    "actions-on-google": "^2.2.0",
    "firebase-admin": "^5.13.1",
    "firebase-functions": "^2.0.2",
    "dialogflow": "^0.6.0",
    "dialogflow-fulfillment": "^0.5.0",
    "mysql": "2.18.1",
    "firebase-tools" : "7.16.1"
  }
}