This felt manageable at first and then the follow-ups kept coming.
Start by clarifying requirements and scale, then walk through the core components of the gateway: routing, rate limiting, observability, and resilience. For each, explain your design choices, trade-offs, and how they integrate to provide a reliable, scalable service.
Pro tip: Emphasize idempotency and graceful degradation: show how you prevent duplicate charges or side effects when retrying, and how the gateway can fall back to cheaper models or cached responses during provider outages.
Ask about expected QPS, latency SLOs, cost sensitivity, compliance needs, and whether the gateway should support streaming or batch. This ensures your design addresses the right priorities.
Explain how to route requests based on model type, cost, latency, or provider health. Include dynamic provider selection, fallback chains, and A/B testing capabilities.
Describe per-user, per-team, and global rate limiting using algorithms like token bucket or sliding window. Discuss distributed rate limiting with Redis and how to handle bursts.
Cover logging, metrics, and tracing for each request, including provider latency, error rates, token usage, and cost. Mention tools like Prometheus, Grafana, and OpenTelemetry.
Discuss retries with exponential backoff and jitter, circuit breakers, timeouts, and fallback strategies. Highlight idempotency keys to avoid duplicate side effects.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.