Hi Maxim, There is still something I do not get...
The gzip_proxied <http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_proxied> default value is set to honor the HTTP/1.0 protocol (which does not have the Vary header and thus is unable to cache different versions of a document) in some proxies. However, the gzip_http_version <http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_http_version> default value is set so that only HTTP/1.1 requests are being compressed... Thus with the default setting it is impossible to compress requests advertising HTTP/1.0. The RFC <http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-2.5> dictates: Intermediaries that process HTTP messages (i.e., all intermediaries other than those acting as a tunnel) MUST send their own HTTP-Version in forwarded messages. In other words, they MUST NOT blindly forward the first line of an HTTP message without ensuring that the protocol version matches what the intermediary understands, and is at least conditionally compliant to, for both the receiving and sending of messages. 'tunnel' is considered different as a 'proxy', as section 2.3 <http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-14#section-2.3> indicates: There are three common forms of HTTP intermediary: proxy, gateway, and tunnel. Thus, any HTTP/1.0 proxy should be seen with a HTTP/1.0 protocol version header... and thus should naturally get an uncompressed version of the page. Non-compliant proxies can be bogus in thousands of way, so there is no point in trying to satisfy them anyway. In the light of these elements, I am still wondering why the default behavior of the gzip module for HTTP/1.1 requests going through a (HTTP/1.1) proxy is to send a disturbing uncompressed version of the page. --- *B. R.* On Sun, Mar 22, 2015 at 6:06 PM, Maxim Dounin <mdou...@mdounin.ru> wrote: > Hello! > > On Sun, Mar 22, 2015 at 03:14:22PM +0100, B.R. wrote: > > > I do not get why you focus on the gzip_vary directive, while I was > > explicitely talking about gzip_proxied. > > The fact that content supposedly compressed might actually not be because > > it contains a 'Via' header is the root cause of our trouble... and you > just > > told me it was for HTTP/1.0 compatibility. > > With HTTP/1.0, there is only one safe option: > > - don't compress anything for proxies. > > With HTTP/1.1, there are two options: > > - don't compress anything for proxies; > > - compress for proxies, but send Vary to avoid incorrect behaviour. > > The second options, which becomes available if you don't care > about HTTP/1.0 compatibility at all, has its downsides I've > talked about. > > -- > Maxim Dounin > http://nginx.org/ > > _______________________________________________ > nginx mailing list > nginx@nginx.org > http://mailman.nginx.org/mailman/listinfo/nginx >
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