Cookie problem with proxy cache

[Gabriel Ramuglia]

I agree. Full vary support for cookies seems like a waste, the
overhead in caching items that will never be requested again outweighs
the benefits. But, caching without regard to cookies, except when a
cookie vary header is there, and then not caching at all, that seems
efficient and useful.

On Wed, Nov 18, 2009 at 12:41 PM, Ole Laursen <olau at iola.dk> wrote:
> Gabriel Ramuglia <gabe at ...> writes:
>> And then, of course, cookies will be sent even when trying to access
>> things like images, css, js files, which will not be changing
>> regardless of the cookie sent. So vary-cookie makes sense to me. I
>> guess if I were caching software, I would just decide not to cache
>> anything when it said vary-cookie, and would then ignore the cookies
>> otherwise, and cache anyway, even if there were cookies. That seems to
>> make the most sense to me.
>
> Yes, exactly. The backend signals that a page depends on a cookie by sending a
> Vary: cookie header. Nginx shouldn't cache and send such a page to everyone.
>
>
> Here's the code in Varnish that handles the Vary header:
>
> http://varnish.projects.linpro.no/browser/trunk/varnish-cache/bin/varnishd/cache_vary.c
>
> I think it constructs a regexp used when looking for a matching object. So my
> assertion about Varnish was wrong, it actually caches the page, but it only
> returns it to a client with the same cookie. Full vary supports looks like it's
> some work:
>
> http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.44
>
> But I'd be happy with just support for Vary: cookie that simply bypasses the
> cache. I had a brief look at the nginx code, but I'm not sure where one would do
> the change?
>
>
> Ole
>
>
>