docker-compose.yaml

version: "3"
services:
  db:
    image: mysql:latest
    environment:
      - MYSQL_ROOT_PASSWORD=rootinha
      - MYSQL_DATABASE=dbzin
    ports:
      - "3306:3306"
  app:
    build: .
    ports:
      - "8080:8080"
    depends_on:
      - db

Dockerfile

FROM node:latest

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 8080

CMD node index.js

index.js

const mysql = require('mysql2')

const connection = mysql.createConnection({
  host     : 'db',
  port: '3306',
  user     : 'root',
  password : 'rootinha',
  database : 'dbzin'
});

connection.connect((error) => {
  if (error) {
    console.error('Error connecting to MySQL database:', error);
  } else {
    console.log('Connected to MySQL database!');
  }
});

// close the MySQL connection
//
connection.end()
 
console.log("NICE!")

package.json

{
  "name": "ntd",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "mysql2": "^3.9.2"
  }
}