Design a rate limiter
Company: Oracle
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
Design a rate limiting system for an API gateway.
Your design should address:
- Rate limits such as "N requests per second/minute" per key (e.g., per user, per IP, per API token).
- Correctness under concurrency and bursty traffic.
- Operation in a distributed, multi-instance gateway.
- What happens on limit exceed (HTTP status, headers, retry guidance).
- Observability and configurability (different limits per endpoint/customer tier).
Overview: This question evaluates a candidate's ability to design scalable, correct distributed rate limiting mechanisms, testing competencies in distributed systems, concurrency control, API gateway behavior, observability, and configurability within the System Design domain.