Ecommerce Workbook: Docker Compose and Database Volumes
Key Takeaways
Multi-Database Architecture Mastery: Production applications often require different databases for different services - MySQL for user management, PostgreSQL for inventory, MongoDB for flexible document storage - all orchestrated seamlessly
Database-Specific Environment Variable Patterns: Each database technology has unique initialization requirements:
Named Volume Strategy for Data Durability: Create dedicated named volumes for each database service to ensure data survives container destruction and restarts (mysql-profile-data, postgres-inventory-data, etc.)
Application-Database Connection Patterns: Applications connect to databases using environment variables that specify connection details - host (container name), port (standard database ports), database name, and credentials
Service Dependency Orchestration: Use depends_on to ensure database containers start before application containers, preventing connection failures during startup
Database Port Standards: Each database runs on its standard port within containers (MySQL: 3306, PostgreSQL: 5432, MongoDB: 27017) - no host port mapping needed for inter-service communication
Volume Mount Path Knowledge: Understanding default data storage paths within database containers (/var/lib/mysql, /var/lib/postgresql/data, /data/db) is essential for proper volume configuration
Application Resilience Patterns: Well-designed applications implement retry logic for database connections, handling temporary network issues during container startup sequences
Production-Ready Architecture: This setup demonstrates enterprise-level microservices architecture with persistent data storage, multiple database technologies, and proper service isolation
Version Management for Database Integration: Database integration represents major version changes (2.0.0) requiring updated documentation, testing, and careful deployment coordination across all dependent services