AdvancedTechnical
5 min

Scaling API Gateways

API GatewayScalabilityNetworking
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Interview Question

What considerations would you make when scaling an API gateway for millions of requests per second?

Key Points to Cover
  • Horizontally scale gateway instances behind load balancers
  • Enable caching, compression, and connection pooling
  • Use async/non-blocking IO for throughput
  • Apply rate limiting, circuit breakers, and retries
  • Ensure observability of latency and errors
Evaluation Rubric
Explains horizontal scaling and LB use30% weight
Optimizes throughput/latency30% weight
Adds reliability features (circuit breakers)20% weight
Mentions monitoring metrics20% weight
Hints
  • 💡Consider Envoy, NGINX, Kong at scale.
Common Pitfalls to Avoid
  • ⚠️Underestimating the importance of network latency and bandwidth between gateway instances and backend services.
  • ⚠️Failing to implement proper caching strategies, leading to unnecessary load on backend systems.
  • ⚠️Using blocking I/O in the gateway implementation, severely limiting its concurrency and throughput.
  • ⚠️Neglecting robust error handling and retry mechanisms, which can exacerbate issues during high load.
  • ⚠️Insufficient or absent monitoring and alerting, leading to slow or no detection of scaling issues.
Potential Follow-up Questions
  • What about multi-region API gateway design?
  • How do you prevent cascading failures?
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