Docker Compose

First PublishedFeb 19, 2026ByAtif Alam

Docker Compose lets you define and run multi-container applications in a single place. You describe services, networks, and volumes in a Compose file (usually docker-compose.yml) and use docker compose up to start everything.

Compose File Basics

services:
  web:
    image: nginx:alpine
    ports:
      - "8080:80"
    depends_on:
      - api

  api:
    build: ./api
    environment:
      - DB_HOST=db
      - DB_PORT=5432
    depends_on:
      - db

  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: app
      POSTGRES_PASSWORD: secret
    volumes:
      - dbdata:/var/lib/postgresql/data

volumes:
  dbdata:

Key Fields

Field	Purpose
services	Each key is a service name (e.g. web, api, db).
image	Use a pre-built image (e.g. nginx:alpine).
build	Build from a Dockerfile (path or context + dockerfile).
ports	Publish ports "host:container".
environment	Environment variables for the container.
volumes	Mount named volumes or bind mounts.
depends_on	Start order (does not wait for health).
networks	Attach services to user-defined networks.

Commands

# Start all services (build if needed, foreground)
docker compose up

# Start in background
docker compose up -d

# Build and start
docker compose up -d --build

# Stop and remove containers (volumes persist by default)
docker compose down

# Stop and remove containers and named volumes
docker compose down -v

# List running services
docker compose ps

# View logs (all services or one)
docker compose logs -f
docker compose logs -f api

Networks

By default Compose creates a single network per project and attaches all services to it. Containers can reach each other by service name (e.g. db, api). To use a custom network:

services:
  web:
    networks:
      - front
  api:
    networks:
      - front
      - back
  db:
    networks:
      - back

networks:
  front: {}
  back: {}

Key Takeaways

• Define services, volumes, and networks in docker-compose.yml; use depends_on for start order.
• docker compose up -d starts the stack; docker compose down stops and removes containers. Use docker compose logs and docker compose ps to inspect.