How would you design readiness, liveness, and startup checks for a Python service?

Separates process survival, traffic readiness, and slow initialization without turning shared dependency failure into a restart storm.

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Liveness answers whether the Python process is alive and able to make progress. Readiness answers whether this worker should receive traffic, and startup protects a slow-initializing process from premature liveness failure. I keep liveness local instead of making it fail whenever a shared database or provider is down. Readiness checks only dependencies and initialization required to serve the application's current contract, with short bounded calls.

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Separates process survival, traffic readiness, and slow initialization without turning shared dependency failure into a restart storm.

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Separates process survival, traffic readiness, and slow initialization without turning shared dependency failure into a restart storm.
Liveness answers whether the Python process is alive and able to make progress. Readiness answers whether this worker should receive traffic, and startup protects a slow-initializing process from premature liveness failure. I keep liveness local instead of making it fail whenever a shared database or provider is down. Readiness checks only dependencies and initialization required to serve the application's current contract, with short bounded calls.
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A FastAPI worker becomes ready after required lifespan setup; a Django service becomes ready after critical configuration and compatible schema are available. Optional capabilities can report degraded status without removing the whole instance. The endpoint avoids expensive business queries and sensitive details. Probe intervals, timeouts, and failure thresholds account for normal latency so a transient pause does not create traffic flapping or restart every replica.

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Putting every dependency in liveness
Running an expensive business query on every probe
Returning secrets in health details

How would you design readiness, liveness, and startup checks for a Python service?

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