Docker Mastery

Build Apps That Deploy Anywhere

Ecommerce Workbook: Docker Compose

Key Takeaways

  • Command-to-YAML Translation: Docker Compose transforms complex multi-terminal docker run commands into clean, readable YAML configurations that define entire application stacks
  • Image Version Strategy: Use semantic versioning (1.0.0) for microservices that will evolve, but keep stable applications (like UI) as latest to indicate they won't change between versions
  • DockerHub Integration Workflow: Push all images to DockerHub first, then reference them in docker-compose.yml, enabling team collaboration and deployment consistency across environments
  • Dependency Chain Management: The depends_on field controls startup order, ensuring dependent services (like UI) start only after their required APIs are running and ready
  • Environment Variable Centralization: Complex environment configurations scattered across multiple command-line flags are organized cleanly within each service definition in the YAML file
  • YAML Syntax Criticality: Proper indentation and spacing in YAML files is essential - incorrect formatting will cause docker-compose to fail with undefined service errors
  • Service Discovery Consistency: Container names in docker-compose.yml become hostnames for inter-service communication, maintaining the same networking patterns as manual Docker operations
  • Port Mapping Strategy: Port mappings in Compose serve primarily for external access and debugging - services communicate directly via internal container ports within the network
  • Error-Driven Development: Missing service definitions are caught immediately by depends_on validation, forcing complete and correct application architecture definition
  • Single Command Orchestration: Replace dozens of individual docker commands and multiple terminal windows with simple docker-compose up and docker-compose down operations