Database Operations
PostgreSQL Connection Refused Debugging Guide
Troubleshoot PostgreSQL connection refused errors across service state, listening addresses, ports, containers, firewalls and client routing. This reference is written for developers who need practical validation behavior, reviewable rules and safe examples rather than copied snippets with no explanation.
Recommended workflow
| Step | Why it matters |
|---|---|
| Resolve the endpoint | Confirm DNS, address family, port and container or service boundary used by the client. |
| Prove the listener | Check PostgreSQL service state and the exact addresses bound by the server. |
| Test network layers | Separate local socket access, host TCP, firewall and cloud policy one hop at a time. |
| Move to authentication | Only inspect pg_hba.conf after a TCP connection reaches PostgreSQL. |
Starter snippet
pg_isready -h host -p 5432 && ss -lntpReview checks
- Compare IPv4 and IPv6 resolution.
- Verify container port publication and service discovery.
- Preserve server logs around startup.
- Avoid exposing PostgreSQL publicly for a quick test.
Common mistakes
- Editing pg_hba.conf for a refused TCP connection.
- Testing localhost from the wrong container.
- Opening port 5432 to the internet.
Validation should help users correct input while protecting systems from bad data. Keep syntax checks, product policy, security review and deliverability checks separate.
Related Formalint references
Continue with Linux Firewall Debugging, Docker Compose Debugging Guide, Postgresql Dba Checklist.