Docker Compose — Compose Dependencies

Learn how to control service startup order, define health checks, and handle dependencies between containers in Docker Compose.

What You Will Learn

#	Topic	Description
1	depends_on Basics	Controlling startup order
2	Condition: service_healthy	Waiting for healthy dependencies
3	Health Checks	Defining health check commands
4	Startup & Shutdown Order	Full lifecycle control
5	Wait Strategies	Application-level waiting
6	Practice Exercises	Hands-on challenges

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Why Dependencies Matter

Without depends_on:              With depends_on + health check:
─────────────────────            ──────────────────────────────
  api starts                      db starts
  db starts                       db health check passes ✓
  api crashes (no db!)            api starts (db ready!)

Simply setting depends_on only controls start order. For true readiness, you need health checks with condition: service_healthy.