docker-compose

What I do

• Create docker-compose.yml for service orchestration
• Define multi-stage builds and service dependencies
• Configure volumes, networks, and environment variables
• Set up health checks and restart policies
• Debug container startup and networking issues
• Manage container lifecycle (start, stop, rebuild)

When to use me

Use me when orchestrating multi-container applications, especially when:

• Setting up local development environments
• Configuring production deployments
• Managing service dependencies and networking
• Debugging container communication issues
• Optimizing image sizes and build times

Common commands

• docker-compose up -d - Start services in detached mode
• docker-compose down - Stop and remove containers
• docker-compose build - Build images
• docker-compose logs -f - Follow logs
• docker-compose exec service sh - Execute command in container
• docker-compose ps - List running containers

Service configuration

services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    volumes:
      - ./data:/app/data
    depends_on:
      - db
    restart: unless-stopped
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3000/health"]
      interval: 30s
      timeout: 10s
      retries: 3

Networking patterns

• Create custom networks for service isolation
• Use service names as hostnames (e.g., db:5432)
• Expose ports only where necessary (internal vs external)
• Configure DNS resolution for service discovery

Volume strategies

• Named volumes for persistent data
• Bind mounts for live code reloading
• Temporary volumes for caches and logs
• Backup named volumes before major changes

Build optimization

• Use multi-stage builds to reduce image size
• Cache dependencies with COPY layers
• Use .dockerignore to exclude unnecessary files
• Build once, run multiple times (no build in production containers)

Health checks

• Define health checks for critical services
• Use depends_on: {condition: service_healthy} for ordering
• Implement readiness endpoints in applications
• Configure appropriate timeouts and retries

Debugging tips

• Use docker-compose logs --tail=100 service for recent logs
• Enter container with docker-compose exec service sh
• Check networking with docker network inspect
• Verify environment variables with docker-compose config
• Use --no-cache flag when troubleshooting builds