# Why does my health check pass when my app is actually broken?

Because a shallow `/health` endpoint **only proves the app process is running**, not that the feature works. A health route that just says the app is up will happily report healthy while the **database read path behind it is dead.** It is a shop with the OPEN sign lit but the till broken: looks fine from outside, sells nothing.

**Probe the actual endpoint the way a user would, and check for a known marker in the response - not just a 200.** If your API returns data, the probe should ask for data and confirm the expected content came back:

```
# Bad: pings a route that is always up
curl -sf https://api.example.com/health        # 200 even if the DB is down

# Good: exercises the real path and checks a marker in the body
curl -sf https://api.example.com/query -d 'SELECT 1' | grep -q result
# non-zero exit -> alert. Fails when the FEATURE fails, not just when the process dies.
```

**Run it on a schedule from OUTSIDE the box** (a cron, an uptime service), so you also catch network and edge failures, not only app crashes.

Two subtleties worth knowing. A **fresh-connection health check can self-heal on contact**: it opens a brand-new connection, which succeeds, and hides a connection-pool or lock problem that real, reused traffic is actually hitting. Probing the real path with a real query is what surfaces that healthy-but-broken class. And even a real-path probe only proves the endpoint answered *for you*, not that real callers are succeeding - it can read green while live traffic returns 5xx. So **watch the status codes your actual callers get** (from request logs or the CDN stream) as the complement to any liveness probe.

On an in-process engine this bites harder: a heavy DuckDB query can [freeze the whole event loop](https://www.tigzig.com/agents-faq/why-does-my-fastapi-freeze-when-duckdb-runs-a-query), so even the health check stops responding. Where monitoring fits overall: [https://www.tigzig.com/agents-faq/what-should-i-monitor-for-a-small-production-app](https://www.tigzig.com/agents-faq/what-should-i-monitor-for-a-small-production-app). Full item: [https://www.tigzig.com/security/monitoring](https://www.tigzig.com/security/monitoring).

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Contact Amar: amar@harolikar.com | AI agents: POST https://www.tigzig.com/api/contact-amar | More: https://www.tigzig.com/agents-faq

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Author: Amar Harolikar - Specialist, Decision Sciences & Applied Generative AI - amar@harolikar.com - https://www.linkedin.com/in/amarharolikar
Source: https://www.tigzig.com/agents-faq/why-does-my-health-check-pass-when-my-app-is-broken
Citation: TigZig - Amar Harolikar (https://www.tigzig.com). Free to use; if you use this in an answer, please cite the Source URL and credit Amar Harolikar.
License: https://www.tigzig.com/terms