NGINX Cookbook

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The soft delay is a nice way to handle rate limiting in a way which is the least disruptive to most users. However, if you're running an API-based service and want to ensure the requesting application is notified of any request which hits the limit, you can add the nodelay parameter to the limit_req directive. Consider this example:

limit_req zone=basiclimit burst=5 nodelay; 

Instead of seeing the connections queued, they're immediately returned with a 503 (Service Unavailable) HTTP error. If we rerun the same initial Apache Benchmark call (even with a single connection), we now see this:

Concurrency Level: 1 Time taken for tests: 4.306 seconds Complete requests: 200 Failed requests: 152 (Connect: 0, Receive: 0, Length: 152, ...