I have an nginx web server sitting in front of a Jetty Java app server running a web application.
I'd like to configure nginx to return a HTTP 503 if the proxied Jetty server is down.
This way when I bring the app server down for maintenance, of if it happens to crash, a 503 is returned to any clients letting them know the site is temporarily unavailable.
However, with the basic configuration, Nginx returns a HTTP 502 Bad Gateway when it can't connect to the proxy_pass location.
Is it possible to configure nginx to report a 503 instead?
You can do so by setting an error page.
With just the contents of Martin Fjordvald's answer I was still getting 502, I didn't have a real maintenance.html page, but this seems to work: