nginx not forwarding POST to @fallback
I fixed the problem by simply rebuilding the most recent version of nginx. The config, as well as the POST and GET forwarding works perfectly. Weirdness.
Your server can return a response with X-Accel-Redirect header pointing a backend url.In this case nginx will make the request to the url and return the response back to the user.No 30[12] redirects, just as if user requested the url in the first place.
http://kovyrin.net/2006/11/01/nginx-x-accel-redirect-php-rails/
Google for other examples.
This is nginx specific, but the idea is featured in lighttpd with X-Sendfile header.
I would not count on POST request parameters passing here.Mirror POST parameters in GET ones of X-Accel-Redirect return,if your backend can accept that.error_page won't pass any indeed.