nginx with NLB - health check succeeds, nginx is not responsive

Question

A customer ran out of disk space in his EC2 machines. Yet, his TCP health check succeeded, but his nginx failed to return HTTP responses.

Has anyone seen this situation before where the health check is successful but nginx is non-responsive?

Accepted Answer

TCP check is only verifying the TCP connection to the host, not the nginx HTTP app response.

You can setup a HTTP check for specific path to test the app response from nginx.  Here is information on the health check for NLB target groups:

https://docs.aws.amazon.com/elasticloadbalancing/latest/network/target-group-health-checks.html

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