Debugging Docker Compose Like a Pro: Hard Lessons from the Trenches

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Docker Compose: a blessing and a curse.

Raise your hand if you’ve ever yelled at a stack of misbehaving containers. Yeah. Same.

Over the past year, I’ve debugged dozens of Dockerized apps—some my own, some inherited messes. Here’s what I wish I’d known earlier.

🚩 Common pain points

• “Works on my machine” syndrome from stale volumes.
• Ports clashing with other services (seriously, who doesn’t run Postgres on 5432?)
• Services depending on others to be ready before they are.

🛠️ Debug like a pro

✅ Check container logs early: docker compose logs -f <service> saves hours.
✅ Run interactively: docker compose run --rm <service> bash to poke around inside.
✅ Use depends_on but also healthchecks: depends_on only waits for container start, not ready. Add healthchecks or custom wait scripts.
✅ Wipe volumes carefully: docker compose down -v clears persistent volumes that can cache issues. Use wisely.

🐛 Weirdest bug I’ve debugged

A Redis service failing silently because another Compose project on the same machine shared the volume path. Ghost data conflicts. Fun times.

Takeaway: Every container is a tiny OS. Debug them like machines, not just services.