Traffic Management for Reliability

We implement multi-tier rate limiting: global limits protect infrastructure capacity, per-tenant limits prevent noisy neighbors, per-endpoint limits protect expensive operations, and per-IP limits mitigate abuse. Limits use token bucket or sliding window algorithms with Redis-backed distributed state. Rate-limited requests get 429 responses with Retry-After headers, not silent drops.

When your service approaches capacity, it should reject excess requests gracefully rather than degrading for everyone. We implement adaptive load shedding based on in-flight request count, CPU utilization, and response latency. Shed requests receive fast 503 responses. Priority headers ensure critical paths (checkout, authentication) are shed last while non-critical paths (analytics, thumbnails) are shed first.

When a downstream dependency fails, your service should stop calling it — not pile on with retries. We implement circuit breakers on every external call: closed state allows normal traffic, open state returns fallback responses, half-open state probes recovery. Circuit state is visible in dashboards and triggers alerts when breakers open. Configuration covers failure thresholds, timeout windows, and recovery probing intervals.

Not all traffic is equal. We configure traffic shaping to prioritize authenticated users over anonymous, paid tier over free tier, and read operations over writes during degraded states. Service mesh routing rules (Istio, Linkerd) or application-level middleware handles the prioritization. The result: your most valuable users get the best experience even under stress.