Docker Container Logs Guide
Use docker logs, timestamps, tailing, service names and Compose context to debug containerized applications safely. This Formalint reference is written for working developers, DBAs and support engineers who need a repeatable debugging path instead of a one-line snippet with no context.
Use the notes below as a practical review order: understand the input, capture evidence, make one small change and verify the result before moving to the next assumption.
When to use this page
Read container logs without losing service context. It is most useful when a small validation or debugging mistake can create noisy tickets, misleading logs or hard-to-review production changes.
Practical workflow
| Step | What to confirm |
|---|---|
| Identify the container | Use names, status and ports before opening logs. |
| Limit output | Start with tail and since filters to avoid drowning in old noise. |
| Correlate timestamps | Compare container logs with API client, proxy and database timestamps. |
Log commands
docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"
docker logs --tail 100 --timestamps container-name
docker logs -f --since 10m container-name
docker compose logs --tail 120 apiReview checklist
- Check whether the container is restarting.
- Use compose service names when the project is Compose-managed.
- Keep secrets out of copied logs.
- Capture the command you used beside the output.
- Inspect healthchecks and exit codes when logs are empty.
Common mistake
A log line without container name, timestamp and service context is easy to misread during an incident.
Formalint is strongest when the page helps the developer decide what the tool cannot prove. Treat every formatter, regex and command as one layer of evidence, not the whole truth.
Frequently asked questions
Why are docker logs empty?
The process may log to a file, exit early, use another logging driver or never start.
Should I follow logs forever?
No. Follow long enough to reproduce, then stop and save focused evidence.
Related Formalint references
Continue with Docker Compose Debugging, Docker Env Files, Nginx 502 504 Debugging.