502 errors with nginx+gunicorn

[Maxim Dounin]

Hello!

On Mon, Sep 08, 2014 at 05:01:07PM -0400, xkillac4 wrote:

> Hi all,
> 
> I am sending large post request to gunicorn/django behind nginx.  If
> gunicorn responds and closes the connection before nginx has finished
> sending the large request body, it causes nginx to issue a 502 Bad Gateway
> response instead of the app server's response.  This scenario happens e.g.,
> if the endpoint requires authentication but the request is not authenticated
> (401 or 403).
> 
> More info here: https://github.com/benoitc/gunicorn/issues/872
> 
> As noted in the linked gunicorn issue, I've worked around this by making
> sure django waits for the entire request to come in before responding.  Not
> sure if this is something you guys are interested in looking into, but
> thought I'd share.

This looks like classic problem, solved with lingering close in 
http world (see [1] for nginx own implementation details).  There 
isn't much nginx can do in this case - it's something to be 
resolved in a backend software.

[1] http://nginx.org/r/lingering_close

-- 
Maxim Dounin
http://nginx.org/