Unable to establish connection between Docker containers: Node application container cannot connect to MySQL container

Question

I am trying to set up a multi-container application using the docker-compose concept.

The containers are creating and running successfully using docker compose up -d command

I can log in to MySQL Shell and it is displaying the database (named todos)-

But the node app's logs are showing the connection error with MySQL

Here's my docker-compose.yml file-

services:
  app:
    image: node:18-alpine
    command: sh -c "yarn install && yarn run dev"
    ports:
      - 3000:3000
    working_dir: /app
    volumes:
      - ./:/app
    environment:
      MYSQL_HOST: mysql
      MYSQL_USER: root
      MYSQL_PASSWORD: secret
      MYSQL_DB: todos
    depends_on:
      - mysql

  mysql:
    image: mysql:8.0
    volumes:
      - todo-mysql-data:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: secret
      MYSQL_DATABASE: todos

volumes:
  todo-mysql-data:

Nodejs application is using this code to connect with MySQL-

const waitPort = require('wait-port');
const fs = require('fs');
const mysql = require('mysql2');

const {
    MYSQL_HOST: HOST,
    MYSQL_HOST_FILE: HOST_FILE,
    MYSQL_USER: USER,
    MYSQL_USER_FILE: USER_FILE,
    MYSQL_PASSWORD: PASSWORD,
    MYSQL_PASSWORD_FILE: PASSWORD_FILE,
    MYSQL_DB: DB,
    MYSQL_DB_FILE: DB_FILE,
} = process.env;

let pool;
async function init() {
    const host = HOST_FILE ? fs.readFileSync(HOST_FILE) : HOST;
    const user = USER_FILE ? fs.readFileSync(USER_FILE) : USER;
    const password = PASSWORD_FILE ? fs.readFileSync(PASSWORD_FILE) : PASSWORD;
    const database = DB_FILE ? fs.readFileSync(DB_FILE) : DB;

    await waitPort({ 
        host, 
        port: 3306,
        timeout: 10000,
        waitForDns: true,
    });

    pool = mysql.createPool({
        connectionLimit: 5,
        host,
        user,
        password,
        database,
        charset: 'utf8mb4',
    });

    return new Promise((acc, rej) => {
        pool.query(
            'CREATE TABLE IF NOT EXISTS todo_items (id varchar(36), name varchar(255), completed boolean) DEFAULT CHARSET utf8mb4',
            err => {
                if (err) return rej(err);

                console.log(`Connected to mysql db at host ${HOST}`);
                acc();
            },
        );
    });
}

What am I doing wrong? Can someone please help debug that?

NOTE-

If anyone wants to set up this demo, I am following the docker documentation example.