ALB - nginx proxy_next_upstream functionality

Question

nginx has a feature called proxy_next_upstream where it will retry a request against another upstream if an error occurs on the 1st upstream it tries, such as an error, timeout, or certain http code:

https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_next_upstream

Does similar functionality exist in an ALB where it retries a request against another target if the 1st target fails?

In my example, I have 2 EC2 webservers behind an ALB, and if I reboot one of them or it has another issue, could the ALB immediately start redirecting traffic to the other EC2?  I have the Health Check at 5 seconds, but hoping to avoid the downtime waiting for the Health Checks to fail.

Or is there another way to avoid downtime in a scenario like this?

Thank you for your help.

Gary Mclean · Answer

If you need to reboot an EC2, remove it from the target group before you reboot it so that the connections are drained and you don’t have the issue waiting for the health checks to time out.

After the reboot add it back in.

You can do this automatically such as when patching using SSM lifecycle.

ALB - nginx proxy_next_upstream functionality

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