CORS headers not being set for a 401 response from upstream.

[ensing]

Thanks Maxim for the documentation link.

I am running into a similar issue. But it is for a 504 server time out.

I'm doing a long-poll, but it is a cross domain long poll GET request. The
client implementation is trying to use CORS. 
It all works fine with when the GET requests returns something. 
But when the server times out (HTTP 504) there is no CORS header information
on the reply and the client code treats it as:
'No 'Access-Control-Allow-Origin' header is present on the requested
resource'

Just extending the keepalive_timeout indefinitely is also not a good idea.

So what is the recommended way to handle a 504. It seems I don't get this in
the client side XmlHttpRequest. The exceptions occurs before.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,250740,251830#msg-251830