Docker Compose

What is Docker Compose ?

Docker Compose is a tool that allows you to define, configure, and run multi-container Docker applications using a single YAML file. With Compose, you can specify all your application’s services, networks, and storage volumes in one place and manage them together with simple commands, making it easier to develop, test, and deploy complex applications.

Why Use Docker Compose?

• Simplifies Multi-Container Management: Instead of running multiple docker run commands, you can start your entire application stack with a single command.

• Consistency Across Environments: Ensures your development, testing, and production environments are the same, reducing “it works on my machine” problems.

• Faster Development Workflow: You can rebuild, start, stop, or scale services quickly without manually handling each container.

• Easier Collaboration: Share the YAML file with your team so everyone can run the same stack easily.

Setups Node.js app with PostgreSQL using Docker Compose in minutes.

This guide works with any Node.js app that uses PostgreSQL, but you can use my example repository: XO-Game Example Repo

What You’ll Build

• Universal setup – works with Express, NestJS, Fastify, etc.

• PostgreSQL + Node.js with Docker Compose – run full stack locally in one command

• Portable containers – run anywhere with Docker

  
  

Prerequisites (2 minutes setup)

• Docker & Docker Compose installed locally

• (Optional) Use the example repo:

Project Structure

Complete Docker Compose setup Guide

Step 1: Create Dockerfile

Step 2: Create docker-compose.yml

This is a Docker Compose configuration file (docker-compose.yml) for a simple XO Game application with a PostgreSQL database and a Node.js backend. Here's a breakdown of what it does:

1. Version

Specifies the Compose file format. Version 3.8 supports modern features like healthchecks, networks, and volume definitions.

2. Services

   PostgreSQL Database

• Runs a lightweight PostgreSQL 15 container.

• Exposes port 5432 to your host for DB access.

• Uses a named volume postgres_data to persist data.

• Connects to the custom xo-network.

• Healthcheck ensures the DB is ready before dependent services start.

3. Node.js Application

• Builds your Node.js app from the local Dockerfile (build: .).

• Exposes app port 8080 to host port 4000.

• Environment variables configure DB connection.

• depends_on ensures app waits until PostgreSQL is healthy.

• Automatically restarts unless explicitly stopped.

4.Volumes

Named volume to persist PostgreSQL data between container restarts.

4. Networks

Creates a custom bridge network allowing app and postgres to communicate internally.

Step 4: Run Locally with Docker Compose

• Your app will be available at: http://localhost:4000

• PostgreSQL listens on: localhost:5432

Local Development & Testing

Start services:

Stop services:

Rebuild images: