Docker Compose Basics
Docker Compose is a tool for defining and running multi-container Docker applications using a simple, declarative YAML configuration file (docker-compose.yml).
1. Why Use Docker Compose?
Instead of typing 5 different docker run commands with long flags for your database, API, cache, and frontend every time you start work, Docker Compose starts your entire application stack with a single command: docker compose up!
2. Anatomy of `docker-compose.yml`
version: '3.8'
services:
# Service 1: Web Frontend
web:
build: .
ports:
- "3000:3000"
environment:
- NODE_ENV=development
- DB_HOST=db
volumes:
- .:/app
- /app/node_modules
depends_on:
- db
# Service 2: PostgreSQL Database
db:
image: postgres:15-alpine
restart: always
environment:
POSTGRES_USER: root
POSTGRES_PASSWORD: secretpassword
POSTGRES_DB: myappdb
ports:
- "5432:5432"
volumes:
- pgdata:/var/lib/postgresql/data
# Named Volumes declaration
volumes:
pgdata:Next Up
Learn how to build a full multi-container stack: Node.js/Python API + MongoDB/Postgres + Redis cache.
Next Lesson: Multi-Container Stack →
