Set Up Compose Stack

Set Up Compose Stack

Configure Docker Compose for multi-service application stacks with databases, caches, and workers.

When to Use

• Running a web app with a database and/or cache
• Setting up a development environment with multiple services
• Orchestrating background workers alongside an API
• Needing reproducible multi-service environments across teams

Inputs

• Required: Application service (language, port, entry point)
• Required: Supporting services needed (database, cache, queue, etc.)
• Optional: Development vs production configuration
• Optional: Existing Dockerfiles for custom services

Procedure

Step 1: Define Core Stack

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgres://appuser:apppass@postgres:5432/appdb
      REDIS_URL: redis://redis:6379
    depends_on:
      postgres:
        condition: service_healthy
      redis:
        condition: service_started
    restart: unless-stopped

  postgres:
    image: postgres:16
    environment:
      POSTGRES_DB: appdb
      POSTGRES_USER: appuser
      POSTGRES_PASSWORD: apppass
    volumes:
      - pgdata:/var/lib/postgresql/data
    ports:
      - "5432:5432"
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U appuser -d appdb"]
      interval: 5s
      timeout: 5s
      retries: 5

  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"
    volumes:
      - redisdata:/data

volumes:
  pgdata:
  redisdata:

Expected: docker compose up starts all services with the app waiting for a healthy database.

Step 2: Add Health Checks

Health checks enable depends_on with condition: service_healthy:

services:
  postgres:
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U appuser -d appdb"]
      interval: 5s
      timeout: 5s
      retries: 5

  redis:
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
      interval: 5s
      timeout: 3s
      retries: 5

  app:
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3000/health"]
      interval: 10s
      timeout: 5s
      retries: 3
      start_period: 10s

Step 3: Configure Networks

services:
  app:
    networks:
      - frontend
      - backend

  postgres:
    networks:
      - backend

  nginx:
    networks:
      - frontend
    ports:
      - "80:80"

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge

This isolates the database from direct external access while the app bridges both networks.

Step 4: Manage Environment Variables

Create .env file (git-ignored):

POSTGRES_PASSWORD=secure_password_here
APP_SECRET=your_secret_key

Reference in compose:

services:
  postgres:
    environment:
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
  app:
    env_file:
      - .env

Create .env.example (committed to git):

POSTGRES_PASSWORD=changeme
APP_SECRET=changeme

Step 5: Add Worker Services

services:
  worker:
    build:
      context: .
      dockerfile: Dockerfile
    command: ["node", "src/worker.js"]
    environment:
      DATABASE_URL: postgres://appuser:apppass@postgres:5432/appdb
      REDIS_URL: redis://redis:6379
    depends_on:
      postgres:
        condition: service_healthy
      redis:
        condition: service_started
    restart: unless-stopped
    deploy:
      replicas: 2

Step 6: Use Profiles for Optional Services

services:
  app:
    # always starts
    build: .

  mailhog:
    image: mailhog/mailhog
    ports:
      - "8025:8025"
    profiles:
      - dev

  adminer:
    image: adminer
    ports:
      - "8080:8080"
    profiles:
      - dev

# Start core services only
docker compose up

# Start with dev tools
docker compose --profile dev up

Step 7: Create Override for Development

docker-compose.override.yml is auto-merged:

services:
  app:
    build:
      target: dev
    volumes:
      - .:/app
      - /app/node_modules
    environment:
      NODE_ENV: development
      DEBUG: "app:*"
    command: ["npm", "run", "dev"]

Step 8: Build and Run

# Build all images
docker compose build

# Start in background
docker compose up -d

# View logs
docker compose logs -f app

# Check service status
docker compose ps

# Stop and remove
docker compose down

# Stop and remove volumes (full reset)
docker compose down -v

Expected: All services start, health checks pass, app connects to database and cache.

On failure: Check docker compose logs <service>. Common issues: port conflicts, missing environment variables, health check timeouts.

Validation

• docker compose up starts all services without errors
• Health checks pass for database and cache
• Application connects to all dependent services
• Named volumes persist data across restarts
• .env is git-ignored; .env.example is committed
• docker compose down cleanly stops everything
• Profiles separate dev tools from production services

Common Pitfalls

• No health checks: depends_on without condition: service_healthy only waits for container start, not readiness.
• Hardcoded passwords in compose: Use .env files or Docker secrets. Never commit passwords.
• Volume mount overwrites: Mounting .:/app overwrites node_modules built in the image. Use an anonymous volume: /app/node_modules.
• Port conflicts: Check docker compose ps and lsof -i :<port> for conflicts.
• version: key: Compose V2 ignores the version: key. Omit it for modern setups.
• WSL path issues: Use /mnt/c/... paths when mounting Windows directories from WSL.

Related Skills

• setup-docker-compose - R-specific Docker Compose configurations
• create-dockerfile - write the Dockerfile that compose references
• create-multistage-dockerfile - build optimized images for the stack
• configure-nginx - add an Nginx reverse proxy to the stack