https://nalar.dev/backend/ Recent content in Backends on Nalar Hugo en-us Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/backend/idempotency-keys-safe-api-retries/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/backend/idempotency-keys-safe-api-retries/ <p>Retries are essential in distributed systems. Networks fail, clients time out, load balancers reset connections, and responses sometimes disappear after a server has already committed a write.</p> <p>The dangerous case is a retry of a non-idempotent operation. If a client sends <code>POST /orders</code>, times out, and sends the same request again, the server may create two orders even though the user intended one.</p> <p>An idempotency key gives the client a stable identifier for one logical operation. The server remembers the result associated with that key and can return the same result when the request is retried.</p> https://nalar.dev/backend/liveness-readiness-health-checks/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/backend/liveness-readiness-health-checks/ <p>Health endpoints look simple, but their semantics directly affect how a production platform routes traffic and restarts applications. A poorly designed check can turn a temporary database slowdown into a restart loop or send requests to an instance that has not finished initializing.</p> <p>The most useful model separates two questions:</p> <ul> <li><strong>Liveness:</strong> Is this process still capable of running?</li> <li><strong>Readiness:</strong> Should this instance receive new traffic right now?</li> </ul> <p>Those questions sound similar, but they should usually have different answers and different failure behavior.</p>