Docker Compose

# Docker Compose > Create docker-compose.yml for multi-service apps You are a Docker DevOps engineer. The user wants to create a docker-compose.yml file for running multiple interconnected services locally. ## What to check first - Run `docker --version` and `docker-compose --version` to confirm both are installed - Verify the services you need (web app, database, cache, etc.) and their image names from Docker Hub or your registry ## Steps 1. Create a `docker-compose.yml` file in your project root with `version: '3.8'` at the top (compatible with Docker Engine 20.10+) 2. Define the `services:` section and list each service as a key (e.g., `web:`, `db:`, `redis:`) 3. For each service, specify the `image:` field or use `build:` with a Dockerfile path if building locally 4. Set `ports:` to map container ports to host ports using `"HOST:CONTAINER"` format (e.g., `"8080:3000"`) 5. Add `environment:` variables or reference a `.env` file with `env_file: .env` for sensitive data 6. Configure `networks:` and `volumes:` for inter-service communication and persistent data storage 7. Use `depends_on:` to control startup order (e.g., web service depends on db service) 8. Run `docker-compose up -d` to start all services in detached mode, then use `docker-compose logs -f` to monitor ## Code ```yaml version: '3.8' services: web: build: . container_name: myapp_web ports: - "8080:3000" environment: - NODE_ENV=production - DATABASE_URL=postgres://user:password@db:5432/myapp - REDIS_URL=redis://cache:6379 depends_on: - db - cache volumes: - ./src:/app/src networks: - app-network restart: unless-stopped db: image: postgres:15-alpine container_name: myapp_db environment: - POSTGRES_USER=user - POSTGRES_PASSWORD=password - POSTGRES_DB=myapp ports: - "5432:5432" volumes: - db_data:/var/lib/postgresql/data networks: - app-network restart: unless-stopped healthcheck: test: ["CMD-SHELL", "pg_isready -U user"] interval: 10s timeout: 5s retries: 5 cache: image: redis:7-alpine container_name: myapp_cache ports: - "6379:6379" volumes: - cache_data:/data networks: - app-network restart: unless-stopped command: redis-server ``` *Note: this example was truncated in the source. See [the GitHub repo](https://github.com/Samarth0211/claude-skills-hub) for the latest full version.* ## Common Pitfalls - Treating this skill as a one-shot solution — most workflows need iteration and verification - Skipping the verification steps — you don't know it worked until you measure - Applying this skill without understanding the underlying problem — read the related docs first ## When NOT to Use This Skill - When a simpler manual approach would take less than 10 minutes - On critical production systems without testing in staging first - When you don't have permission or authorization to make these changes ## How to Verify It Worked - Run the verification steps documented above - Compare the output against your expected baseline - Check logs for any warnings or errors — silent failures are the worst kind ## Production Considerations - Test in staging before deploying to production - Have a rollback plan — every change should be reversible - Monitor the affected systems for at least 24 hours after the change --- *From [CLSkills.in](https://clskills.in/browse) — 2,300+ free Claude Code skills*