docker-compose

Goal: reproducible multi-service environments that start cleanly. Use for: - running an app with its databases and dependencies locally - standing up integration-test environments - reviewing compose files for correctness and safety Workflow: 1. Define one service per container with a clear image and build. 2. Use healthchecks and depends_on conditions for startup order. 3. Pass configuration via environment and .env, not hardcoding. 4. Persist data with named volumes; mount code for dev only. 5. Define networks to isolate and connect services. 6. Verify a clean up/down cycle from scratch. Practices: - pin image versions, not latest - healthchecks so dependents wait for readiness - named volumes for stateful services - separate override files for dev vs. test Rules: - never bake secrets into images or compose files - pin versions for reproducibility - make depends_on wait on health, not just start - keep the environment disposable and rebuildable