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API Gateway Monitoring

Links: 102 AWS DVA Index

Monitoring, Logging & Tracing

CloudWatch Logs

  • Enable CloudWatch logging at the Stage level (with Log Level)
  • Can override settings on a per API basis (ex: ERROR, DEBUG, INFO)
  • Log contains information about request/response body

X-Ray

  • Enable tracing to get extra information about requests in API Gateway
  • X-Ray API Gateway + AWS Lambda gives you the full picture

CloudWatch Metrics

  • Metrics are by stage, Possibility to enable detailed metrics
  • There are two types of API logging in CloudWatch: execution logging and access logging.
  • CacheHitCount & CacheMissCount: efficiency of the cache
    • CacheMissCount tracks the number of requests served from the backend in a given period, when API caching is enabled.
    • CacheHitCount track the number of requests served from the API cache in a given period.
  • Count: The total number API requests in a given period.
  • IntegrationLatency: The time between when API Gateway relays a request to the backend and when it receives a response from the backend.
  • Latency: The time between when API Gateway receives a request from a client and when it returns a response to the client.
    • The latency includes the integration latency and other API Gateway overhead.
    • Latency > IntegrationLatency
How to differentiate between integration latency and latency?
  • Client present means latency.
  • Relays present means integration latency.
  • 4XXError (client-side) & 5XXError (server-side)
The maximum amount of time an API Gateway can perform any request is 29s so if Latency or IntegrationLatency is > 29s then we will see a timeout from API Gateway

API Throttling

  • Account Limit
    • API Gateway throttles requests at 10000 rps across all API. This means that if one of the APIs is under heavy use then other APIs can also be throttled.
    • Soft limit that can be increased upon request
  • In case of throttling => 429 Too Many Requests (retriable error). Client side error.
  • Can set Stage limit & Method limits to improve performance
  • Or you can define Usage Plans to throttle per customer
Just like Lambda Concurrency, if one API that is overloaded, if not limited, can cause the other APIs to be throttled

Errors

  • 4XX means Client errors
    • 400: Bad Request
    • 403: Access Denied, WAF filtered
    • 429: Quota exceeded, Throttle
  • 5XX means Server errors
    • 502: Bad Gateway Exception, usually for an incompatible output returned from a Lambda proxy integration backend and occasionally for out-of-order invocations due to heavy loads.
      • Like returning XML instead of JSON when using lambda proxy.
    • 503: Service Unavailable Exception. Backend is unavailable.
      • No target groups.
    • 504: Integration Failure.
      • Example: Endpoint Request Timed-out Exception
      • API Gateway requests time out after 29s maximum

Last updated: 2023-02-24