Are numbered captures available to the proxy cache key construct?

[Maxim Dounin]

Hello!

On Mon, Sep 20, 2010 at 07:24:30AM -0400, portante wrote:

> Hi Folks,
> 
> Can somebody comment on whether proxy_cache_key is supposed to be able
> to handle # captures? I believe the below example shows how I want to
> use it, but I can't get it to work.
> 
> Thanks,
> 
> -peter
> 
> 
> [code]
> location    ~   ^/api/rest/\d+/(.+)/.+/*$ {
>     proxy_cache             apiCache;
>     proxy_cache_valid       200  7d;
>     proxy_cache_use_stale   updating;
>     proxy_cache_key         "$host.$1";
>     if ($upstream_http_content_encoding !~* "") { gzip off; }
>     proxy_pass              http://127.0.0.1:8080$request_uri;
> }
> [/code]

Regexp match in "if" directive will be executed (and will reset 
enumerated captures) before proxy module will have cance to grab 
$1.  Use named captures as available in 0.8.25+ to avoid such 
problems.

Additionally, "if" directive in question is useless due to the 
following reasons:

- $upstream_* variables are only available after nginx got reply 
  from upstream, while rewrite directives are executed at rewrite 
  phase - before we even send request to upstream.

- gzip module is smart enough to don't re-encode replies which 
  already have content-encoding applied.

Maxim Dounin