Reliability

How to roll out database schema changes safely in production without breaking reads, writes, deployments, or mixed-version application traffic.

How to write API integration tests that verify real persistence, auth rules, contracts, idempotency, and failure handling across request boundaries.

How idempotency keys prevent duplicate API writes, repeated side effects, and race conditions when clients retry under uncertain network behavior.

How rate limiting and backpressure protect microservices under overload, with practical implementation patterns, rollout advice, and failure signals.

How circuit breakers contain cascading failure in microservices, with practical guidance on thresholds, fallback behavior, and production metrics.