# Docker Compose configuration for QR Code Manager
# This file defines the containerized deployment of the QR Code Manager application
version: '3.8'

services:
  qr-manager:
    # Build the Docker image from the Dockerfile in the current directory
    build: .
    
    # Set a custom container name for easier identification and management
    container_name: qr-code-manager
    
    # Automatically restart the container unless explicitly stopped
    # Options: no, always, unless-stopped, on-failure
    restart: unless-stopped
    
    # Port mapping: host_port:container_port
    # Maps host port 8066 to container port 5000 (where Flask/Gunicorn runs)
    # Access the app at: http://localhost:8066 or https://your-domain (via reverse proxy)
    ports:
      - "8066:5000"
    
    # Load environment variables from .env file
    # Contains production settings like SECRET_KEY, ADMIN_USERNAME, etc.
    env_file:
      - .env
    
    # Additional environment variables set directly in compose
    # FLASK_ENV=production enables production mode with Gunicorn server
    environment:
      - FLASK_ENV=production
    
    # Volume mounts: host_path:container_path
    # Persist data and files outside the container for backup and updates
    volumes:
      # QR code images - stores generated PNG files
      - /opt/qr/qr_codes:/app/app/static/qr_codes
      
      # Logo files - stores uploaded custom logos for QR codes
      - /opt/qr/logos:/app/app/static/logos
      
      # Flask session files - stores user session data
      # Uses /app/flask_session to avoid permission issues (mapped from /tmp/flask_session in container)
      - /opt/qr/sessions:/app/flask_session
      
      # Application data - stores JSON databases (link_pages.json, qr_codes.json, short_urls.json)
      - /opt/qr/persistent:/app/data
    
    # Health check configuration - monitors container health
    # Ensures the application is responding correctly
    healthcheck:
      # Command to test application health - checks the /health endpoint
      test: ["CMD", "python", "-c", "import requests; requests.get('http://localhost:5000/health')"]
      
      # How often to run the health check
      interval: 30s
      
      # Maximum time to wait for health check response
      timeout: 10s
      
      # Number of consecutive failures before marking as unhealthy
      retries: 3
      
      # Grace period before starting health checks (allows app startup time)
      start_period: 10s
    
    # Docker labels for metadata and container management
    # Useful for monitoring, backup scripts, and documentation
    labels:
      - "com.example.description=QR Code Manager Application"
      - "com.example.service=qr-manager"

# Network configuration
# Creates a custom network for better container isolation and communication
networks:
  default:
    # Custom network name for the QR Manager application
    name: qr-manager-network