The two-flavor thing tripped me up at first.
Start by clarifying requirements and scale, then design a high-level architecture that separates inbound and outbound rate limiting concerns. Explain the algorithms and data stores for each, and finally discuss Docker containerization and deployment considerations.
Pro tip: Emphasize that rate limiting should be configurable and observable; mention using Redis for distributed counters and adding metrics for monitoring. Also, highlight the importance of graceful degradation and retry strategies for outbound calls.
Ask about expected traffic, number of clients, upstream API limits, and whether rate limiting needs to be distributed. This sets the context for design decisions.
Choose an algorithm (e.g., token bucket, sliding window) and a storage mechanism (e.g., Redis) to enforce per-client quotas. Discuss how to identify clients (API keys, IP) and handle bursts.
Implement throttling for calls to upstream APIs using a similar algorithm, but consider global limits and queueing. Discuss retry logic, backoff, and circuit breakers.
Describe how to package the application and dependencies into Docker containers, including configuration for rate limiting parameters and integration with Redis. Mention orchestration (e.g., Docker Compose, Kubernetes) for scalability.
Compare algorithms (e.g., token bucket vs. leaky bucket), storage options, and deployment strategies. Highlight the need for monitoring, logging, and alerting on rate limit breaches.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
The 'what would you build next' section is deceptively annoying to write.
Treat the README as a product deliverable that demonstrates engineering communication and judgment. Structure it for multiple audiences: a new developer running it, an API consumer, a reviewer evaluating trade-offs, and a lead assessing future direction. Be explicit about assumptions, constraints, and what you deliberately left out.
Pro tip: Include a 'Known Limitations' or 'What I'd Do Differently' section alongside 'What I'd Build Next' — it signals intellectual honesty and self-awareness, which senior engineers value more than a polished but uncritical write-up.
Document prerequisites, environment variables, install commands, and a single command to run the project. Include a quick smoke test or example request so the reader can verify it works in under five minutes.
List endpoints or public interfaces with method, path, request/response schemas, status codes, and one concrete example per endpoint. Note authentication, rate limits, and error formats.
Explain key architectural decisions (e.g., database choice, sync vs async, monolith vs services) with the alternatives considered and why you chose this path. Tie each trade-off to a constraint like time, scale, or team size.
Prioritize future work by impact and effort, and connect it to current limitations. Show you understand the product roadmap, not just the code.
Read the README as if you're a new hire on day one. Ensure commands are copy-pasteable, links work, and the tone is concise and professional. Add a table of contents for longer docs.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.