GZIP problem with backend hosts

Igor Sysoev is at rambler-co.ru
Fri Aug 29 14:15:40 MSD 2008

On Fri, Aug 29, 2008 at 11:04:57AM +0100, Alan Williamson wrote:

> Igor Sysoev wrote:
> >On Fri, Aug 29, 2008 at 09:41:42AM +0100, Alan Williamson wrote:
> >
> >>no one got anything input here?
> >>
> >>seems to be a fairly big failing in NGINX here.  Why would it spend 
> >>extra time and resources decompressing outgoing content
> >
> >nginx can not decompress proxied response.
> >In your case probably backend sends uncompressed response.
> okay so lets ask the question another way.
> Scenario#1:
>   Hit Backend#1 directly; get GZIP'd content
> Scenario#2:
>   Hit nginx which then proxies to Backend#1; get raw content
> Soooo ... either ... nginx is decompressing, which you claim it is not, 
> which leaves that nginx isn't passing on all the HTTP headers to the 
> backend, including the all important:
>   "Accept-Encoding: gzip,deflate"
> ?

If you did not set
   proxy_set_header  Accept-Encoding  "";

then nginx will pass it backend.

I do not know conditions when Amazon may refuse to compresses response,
it may have simillar limits as nginx has:

1) gzip_http_version: nginx by default compresses HTTP/1.1 requests only,
   Amazon may do the same. nginx talks to backend using HTTP/1.0 while
   browsers usually use HTTP/1.1.

2) gzip_proxied: nginx by default disables compression if a request has
   "Via" header.

Igor Sysoev

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