API Gateway 429 errors.

HTTP 429 Too Many Requests is a response status code that indicates the user has sent too many requests in a given amount of time ("rate limiting"). In the context of API Gateway, this typically means that the client is making requests to your API at a rate that exceeds the allowed limits.

Here are steps to address API Gateway 429 errors:

1. Check Throttling Settings:
   • Log in to the AWS Management Console, navigate to API Gateway, and select your API. Review the throttling settings for your stages and resources. Make sure they are configured appropriately based on your expected traffic patterns.
2. Review Usage Plans:
   • If you're using usage plans, check the quota and rate limits defined in the usage plan. Ensure that the limits are set to accommodate the expected traffic.
3. Check API Key Usage:
   • If your API requires API keys, ensure that the clients are using valid keys and not exceeding their assigned quotas.
4. Review CloudWatch Metrics:
   • Go to CloudWatch and navigate to the metrics for your API Gateway deployment. Look for spikes in request counts or errors. This can help you identify periods of high traffic.
5. Implement Exponential Backoff:
   • Encourage clients to implement exponential back-off and retries for their requests. This can help spread out the load and reduce the likelihood of hitting rate limits.
6. Consider Caching:
   • Implement caching where appropriate to reduce the number of requests hitting your API.
7. Optimize API Design:
   • Review your API design to ensure it's efficient. For example, avoid unnecessary chatty APIs that require multiple requests to accomplish a task.
8. Implement Throttling at Different Levels:
   • Consider implementing throttling at different levels such as at the API level, resource level, or method level based on your specific use case.
9. Monitor Traffic Patterns:
   • Regularly monitor your API traffic patterns. Use CloudWatch alarms to be notified of unusual spikes in traffic.
10. Consider Auto Scaling:
    • If your backend can handle it, consider implementing auto-scaling to automatically adjust resources based on traffic patterns.
11. Request a Quota Increase:
    • If you consistently exceed the default limits and your use case justifies it, you can request a quota increase from AWS Support.
12. Review Documentation and Tutorials:
    • Review AWS documentation and tutorials related to API Gateway to ensure that you're following best practices.

Remember that 429 errors are typically a sign that your API is receiving more traffic than it's configured to handle. Adjusting your throttling settings and optimizing your application can help ensure smooth and reliable API performance.