Node js mysql Running into the ECONNREFUSED error

Question

New to js and node and I've got an app.js that will query a database and I query it using a pool so I have a file called db.js that looks like this

const mysql = require('mysql2/promise');

const config = {db: {host: 'localhost',user: 'root',password: '',database: 'school',port:'3308',waitForConnections: true,connectionLimit: 2,queueLimit: 0,},};

const pool = mysql.createPool(config.db);

async function query(sql, params) {

const [rows, fields] = await pool.execute(sql, params);

return rows;

}

module.exports = {query,}

However after running docker-compose --build in the terminal I run into this error

/src/node_modules/mysql2/promise.js:359

test-app-1 | const localErr = new Error();

test-app-1 | ^

test-app-1 |

test-app-1 | Error: connect ECONNREFUSED 127.0.0.1:3308

test-app-1 | at PromisePool.execute (/src/node_modules/mysql2/promise.js:359:22)

test-app-1 | at Object.query (/src/app/services/db.js:20:39)

test-app-1 | at /src/app/app.js:17:8

test-app-1 | at Layer.handle [as handle_request] (/src/node_modules/express/lib/router/layer.js:95:5)

test-app-1 | at next (/src/node_modules/express/lib/router/route.js:137:13)

test-app-1 | at Route.dispatch (/src/node_modules/express/lib/router/route.js:112:3)

test-app-1 | at Layer.handle [as handle_request] (/src/node_modules/express/lib/router/layer.js:95:5)

test-app-1 | at /src/node_modules/express/lib/router/index.js:281:22

test-app-1 | at Function.process_params (/src/node_modules/express/lib/router/index.js:341:12)

test-app-1 | at next (/src/node_modules/express/lib/router/index.js:275:10) {

test-app-1 | code: 'ECONNREFUSED',

test-app-1 | errno: -111,

test-app-1 | sql: undefined,

test-app-1 | sqlState: undefined,

test-app-1 | sqlMessage: undefined

test-app-1 | }

The requests that don't require the database open fine eg http://127.0.0.1:3000/ but the ones that do query the database fall to this error. I can see the error stems from a file in a module but I don't know how to go about fixing this. My code for requests in my app.js file look like this

app.get("/", function(req, res) {

res.send("Main Page");});

app.get('/class', function(req,res) {

var sql = 'SELECT * FROM class ';

db.query(sql).then(results => {

console.log(results);

res.json(results);});})

And my index.js file looks like this

"use strict";
console.log("entrypoint");
const app = require("./app/app.js");

I notice the error stems from a module file but I don't want to tamper with it due to my inexperience.

Answer 1

As you are using docker containers for the app and mysql server, and in the error you shared is written:

| Error: connect ECONNREFUSED 127.0.0.1:3308 

To me seems, your docker's trying to connect to port 3308 in your app container instead of connecting to mysql container.

It seems a docker-composer configuration problem.