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Purushotam Adhikari
Purushotam Adhikari

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Multi-Container Applications with Docker Compose: Real-World Examples

#webdev #programming #docker #containers

Modern applications rarely run in isolation. Whether you're building a web application with a database, setting up a microservices architecture, or creating a development environment that mirrors production, you'll likely need multiple containers working together. Docker Compose makes orchestrating these multi-container applications straightforward and reproducible.

In this article, we'll explore practical, real-world examples of Docker Compose configurations that you can adapt for your own projects.

What is Docker Compose?

Docker Compose is a tool for defining and running multi-container Docker applications. Using a YAML file, you can configure your application's services, networks, and volumes, then spin up your entire stack with a single command.

Key benefits include:

  • Reproducible environments across development, testing, and production
  • Simplified orchestration of complex multi-service applications
  • Easy scaling and service management
  • Network isolation and service discovery out of the box

Example 1: Full-Stack Web Application (MEAN Stack)

Let's start with a complete web application stack: MongoDB, Express.js API, Angular frontend, and Node.js backend.

version: '3.8' services: # MongoDB Database mongodb: image: mongo:6.0 container_name: mean_mongodb restart: unless-stopped environment: MONGO_INITDB_ROOT_USERNAME: admin MONGO_INITDB_ROOT_PASSWORD: password123 MONGO_INITDB_DATABASE: meanapp ports: - "27017:27017" volumes: - mongodb_data:/data/db - ./mongo-init.js:/docker-entrypoint-initdb.d/mongo-init.js:ro networks: - mean_network # Node.js API Backend api: build: context: ./backend dockerfile: Dockerfile container_name: mean_api restart: unless-stopped environment: NODE_ENV: development MONGODB_URI: mongodb://admin:password123@mongodb:27017/meanapp?authSource=admin JWT_SECRET: your-jwt-secret-key PORT: 3000 ports: - "3000:3000" volumes: - ./backend:/app - /app/node_modules depends_on: - mongodb networks: - mean_network # Angular Frontend frontend: build: context: ./frontend dockerfile: Dockerfile container_name: mean_frontend restart: unless-stopped environment: - NODE_ENV=development ports: - "4200:4200" volumes: - ./frontend:/app - /app/node_modules depends_on: - api networks: - mean_network # Nginx Reverse Proxy nginx: image: nginx:alpine container_name: mean_nginx restart: unless-stopped ports: - "80:80" volumes: - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro depends_on: - frontend - api networks: - mean_network volumes: mongodb_data: networks: mean_network: driver: bridge
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Key Features:

  • MongoDB with persistent data storage
  • API backend with environment-specific configuration
  • Frontend development server with hot reload
  • Nginx reverse proxy for routing
  • Custom network for service communication

Example 2: E-commerce Platform with Microservices

Here's a more complex example showing a microservices-based e-commerce platform:

version: '3.8' services: # API Gateway api-gateway: image: nginx:alpine container_name: ecommerce_gateway ports: - "80:80" - "443:443" volumes: - ./gateway/nginx.conf:/etc/nginx/nginx.conf:ro - ./gateway/ssl:/etc/nginx/ssl:ro depends_on: - user-service - product-service - order-service networks: - ecommerce_network # User Service user-service: build: ./services/user-service container_name: user_service environment: DATABASE_URL: postgresql://user:password@user_db:5432/users REDIS_URL: redis://redis:6379 JWT_SECRET: ${JWT_SECRET} depends_on: - user_db - redis networks: - ecommerce_network deploy: replicas: 2 user_db: image: postgres:15 container_name: user_database environment: POSTGRES_DB: users POSTGRES_USER: user POSTGRES_PASSWORD: password volumes: - user_db_data:/var/lib/postgresql/data networks: - ecommerce_network # Product Service product-service: build: ./services/product-service container_name: product_service environment: DATABASE_URL: postgresql://product:password@product_db:5432/products ELASTICSEARCH_URL: http://elasticsearch:9200 depends_on: - product_db - elasticsearch networks: - ecommerce_network product_db: image: postgres:15 container_name: product_database environment: POSTGRES_DB: products POSTGRES_USER: product POSTGRES_PASSWORD: password volumes: - product_db_data:/var/lib/postgresql/data networks: - ecommerce_network # Order Service order-service: build: ./services/order-service container_name: order_service environment: DATABASE_URL: postgresql://order:password@order_db:5432/orders RABBITMQ_URL: amqp://guest:guest@rabbitmq:5672/ PAYMENT_SERVICE_URL: http://payment-service:3000 depends_on: - order_db - rabbitmq networks: - ecommerce_network order_db: image: postgres:15 container_name: order_database environment: POSTGRES_DB: orders POSTGRES_USER: order POSTGRES_PASSWORD: password volumes: - order_db_data:/var/lib/postgresql/data networks: - ecommerce_network # Payment Service payment-service: build: ./services/payment-service container_name: payment_service environment: STRIPE_SECRET_KEY: ${STRIPE_SECRET_KEY} WEBHOOK_SECRET: ${STRIPE_WEBHOOK_SECRET} networks: - ecommerce_network # Shared Services redis: image: redis:7-alpine container_name: ecommerce_redis command: redis-server --appendonly yes volumes: - redis_data:/data networks: - ecommerce_network rabbitmq: image: rabbitmq:3-management container_name: ecommerce_rabbitmq environment: RABBITMQ_DEFAULT_USER: admin RABBITMQ_DEFAULT_PASS: password ports: - "15672:15672" # Management UI volumes: - rabbitmq_data:/var/lib/rabbitmq networks: - ecommerce_network elasticsearch: image: docker.elastic.co/elasticsearch/elasticsearch:8.8.0 container_name: ecommerce_elasticsearch environment: - discovery.type=single-node - xpack.security.enabled=false volumes: - elasticsearch_data:/usr/share/elasticsearch/data networks: - ecommerce_network volumes: user_db_data: product_db_data: order_db_data: redis_data: rabbitmq_data: elasticsearch_data: networks: ecommerce_network: driver: bridge
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Example 3: Development Environment with Monitoring

This example shows a development setup with comprehensive monitoring and logging:

version: '3.8' services: # Main Application app: build: . container_name: myapp environment: - NODE_ENV=development - DATABASE_URL=postgresql://postgres:password@db:5432/myapp ports: - "3000:3000" volumes: - .:/app - /app/node_modules depends_on: - db - redis networks: - app_network logging: driver: "json-file" options: max-size: "10m" max-file: "3" # Database db: image: postgres:15 container_name: myapp_db environment: POSTGRES_DB: myapp POSTGRES_USER: postgres POSTGRES_PASSWORD: password ports: - "5432:5432" volumes: - postgres_data:/var/lib/postgresql/data - ./init.sql:/docker-entrypoint-initdb.d/init.sql networks: - app_network # Redis Cache redis: image: redis:7-alpine container_name: myapp_redis ports: - "6379:6379" networks: - app_network # Prometheus (Metrics) prometheus: image: prom/prometheus:latest container_name: prometheus ports: - "9090:9090" volumes: - ./monitoring/prometheus.yml:/etc/prometheus/prometheus.yml - prometheus_data:/prometheus command: - '--config.file=/etc/prometheus/prometheus.yml' - '--storage.tsdb.path=/prometheus' - '--web.console.libraries=/etc/prometheus/console_libraries' - '--web.console.templates=/etc/prometheus/consoles' networks: - app_network # Grafana (Visualization) grafana: image: grafana/grafana:latest container_name: grafana ports: - "3001:3000" environment: - GF_SECURITY_ADMIN_PASSWORD=admin volumes: - grafana_data:/var/lib/grafana - ./monitoring/grafana/dashboards:/etc/grafana/provisioning/dashboards - ./monitoring/grafana/datasources:/etc/grafana/provisioning/datasources networks: - app_network # Jaeger (Distributed Tracing) jaeger: image: jaegertracing/all-in-one:latest container_name: jaeger ports: - "16686:16686" - "14268:14268" environment: - COLLECTOR_OTLP_ENABLED=true networks: - app_network # ELK Stack for Logging elasticsearch: image: docker.elastic.co/elasticsearch/elasticsearch:8.8.0 container_name: elasticsearch environment: - discovery.type=single-node - xpack.security.enabled=false volumes: - elasticsearch_data:/usr/share/elasticsearch/data networks: - app_network logstash: image: docker.elastic.co/logstash/logstash:8.8.0 container_name: logstash volumes: - ./monitoring/logstash/pipeline:/usr/share/logstash/pipeline depends_on: - elasticsearch networks: - app_network kibana: image: docker.elastic.co/kibana/kibana:8.8.0 container_name: kibana ports: - "5601:5601" environment: - ELASTICSEARCH_HOSTS=http://elasticsearch:9200 depends_on: - elasticsearch networks: - app_network volumes: postgres_data: prometheus_data: grafana_data: elasticsearch_data: networks: app_network: driver: bridge
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Best Practices and Tips

1. Use Environment Variables

Keep sensitive data and environment-specific configurations in .env files:

# .env POSTGRES_PASSWORD=your_secure_password JWT_SECRET=your_jwt_secret STRIPE_SECRET_KEY=sk_test_your_stripe_key
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2. Health Checks

Add health checks to ensure services are ready:

services: api: # ... other config healthcheck: test: ["CMD", "curl", "-f", "http://localhost:3000/health"] interval: 30s timeout: 10s retries: 3 start_period: 40s
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3. Resource Limits

Prevent services from consuming too many resources:

services: app: # ... other config deploy: resources: limits: cpus: '0.5' memory: 512M reservations: cpus: '0.25' memory: 256M
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4. Multi-Stage Builds

Optimize your Docker images with multi-stage builds:

# Dockerfile FROM node:18-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm ci --only=production FROM node:18-alpine AS runtime WORKDIR /app COPY --from=builder /app/node_modules ./node_modules COPY . . EXPOSE 3000 CMD ["npm", "start"]
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Common Commands

Here are essential Docker Compose commands for managing your applications:

# Start all services docker-compose up -d # View logs docker-compose logs -f [service_name] # Scale a service docker-compose up -d --scale api=3 # Stop all services docker-compose down # Remove everything including volumes docker-compose down -v # Rebuild and start docker-compose up -d --build # Execute commands in running containers docker-compose exec api npm run migrate
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Troubleshooting Common Issues

1. Port Conflicts

If you get port binding errors, check for conflicting services:

# Check what's using a port lsof -i :3000 # or netstat -tulpn | grep :3000
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2. Network Issues

Services can't communicate? Verify they're on the same network:

# Inspect networks docker network ls docker network inspect <network_name>
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3. Volume Permissions

Permission issues with mounted volumes:

services: app: # Set user ID to match host user user: "${UID}:${GID}"
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Conclusion

Docker Compose transforms complex multi-container applications into manageable, reproducible deployments. Whether you're building a simple web app or a complex microservices architecture, these examples provide a solid foundation you can build upon.

The key is to start simple and gradually add complexity as your application grows. Remember to use environment variables for configuration, implement proper health checks, and leverage Docker's networking capabilities for service discovery.

What multi-container setup are you planning to build? Share your Docker Compose configurations and experiences in the comments below!

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