docker-compose.yml

# Docker Compose for teaching multi-container applications
# This file demonstrates:
# - Service orchestration
# - Container networking
# - Volume management
# - Environment configuration
# - Service dependencies

services:
  # Application service
  app:
    build: .                                                           # Build from Dockerfile
    container_name: landmark-app                                       # Container name
    ports:
      - "3000:3000"                                                    # Map port 3000
    environment:
      # Database connection string
      # Format: mysql://user:password@host:port/database
      # 'db' is the service name (DNS resolution)
      - DATABASE_URL=mysql://landmark:landmark123@db:3306/landmark_devops
      - NODE_ENV=development
    depends_on:
      - db                                                             # Wait for db service to start
    networks:
      - landmark-network                                               # Connect to custom network
    # Uncomment for development with hot reload
    # volumes:
    #   - ./client:/app/client
    #   - ./server:/app/server

  # Database service
  db:
    image: mysql:8.0                                            # Use official MySQL image
    container_name: landmark-db                                        # Container name
    environment:
      # MySQL root password
      - MYSQL_ROOT_PASSWORD=root123
      # Database to create
      - MYSQL_DATABASE=landmark_devops
      # Non-root user for application
      - MYSQL_USER=landmark
      - MYSQL_PASSWORD=landmark123
    ports:
      - "3307:3306"                                                    # Map port 3307 -> 3306
    volumes:
      # Named volume for persistent data
      # Data survives container restart
      - db_data:/var/lib/mysql
    networks:
      - landmark-network                                               # Connect to custom network
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "localhost"]
      interval: 10s
      timeout: 5s
      retries: 5

# Named volumes for persistent storage
volumes:
  db_data:
    driver: local

# Custom network for service communication
networks:
  landmark-network:
    driver: bridge