Bad default for proxy_cache_key

[Maxim Dounin]

Hello!

On Sun, Jun 29, 2014 at 06:15:56PM -0300, Bráulio Bhavamitra wrote:

> Hello all,
> 
> I stucked a while with a config problem where proxy_cache_key default value
> was $scheme$proxy_host$uri$is_args$args".
> 
> Then I realized it really didn't make. A better value
> $scheme$host$uri$is_args$args" is much more reasonable, as the reverse
> proxy requests comes from many server {} with multiple server name and
> aliases.
> 
> Shouldn't the default be changed?

The default key is to identify resources nginx requests from 
upstream servers.  That is, these are the same:

    server {
        server_name bar;

        location / {
            proxy_pass http://foo.example.com;
        }
    }

    server {
        server_name bazz;

        location / {
            proxy_pass http://foo.example.com;
        }
    }

While these are different:


    server {
        server_name foo;

        location / {
            set $backend "foo.example.com";

            if ($user_is_admin) {
                set $backend "admin.example.com";
            }

            proxy_pass http://$backed;
        }
    }


If in your case multiple such resources are equal or different 
based on other factors (likely, due to "proxy_set_header Host ..." 
in your configuration), you are free to change proxy_cache_key 
accordingly.

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