Connect to MySQL from Node.js

The application lessons use Node.js as an optional track. You can follow the database and operations lessons without it.

Install the promise-based mysql2 driver:

npm install mysql2

Create a bounded pool from environment variables:

import mysql from 'mysql2/promise'

export const pool = mysql.createPool({
  host: process.env.DB_HOST,
  port: Number(process.env.DB_PORT ?? 3306),
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_NAME,
  waitForConnections: true,
  connectionLimit: 5,
  queueLimit: 20,
  connectTimeout: 5000,
  enableKeepAlive: true,
})

Five connections is an example budget, not a universal value. Count every application replica before choosing the limit.

Call await pool.end() when a script or worker shuts down. A long-running web process keeps the pool open until its shutdown hook runs.