http_proxy_module is included, it's what we use to proxy to the back-ends app servers.

It will retry the same server `max_fails` amount of times, until it will flag the node as down and not try again. Nginx will wait `fail_timeout` amount of time before it tries that upstream again to check if it is up. I believe we're using the defaults on those, and nginx documentation has crashed so I can't get that date for you right now.