How to send proxy cache status to backend server?
mdounin at mdounin.ru
Thu Mar 27 11:32:58 UTC 2014
On Thu, Mar 27, 2014 at 03:01:22PM +0530, Makailol Charls wrote:
> Hi Maxim,
> Apart from passing cache status to backend, would it be possible to send
> some other headers which are stored in cache?
> For example, If backed sets header "Foo : Bar" , which is stored in cache.
> Now when cache is expired , request will be sent to backend. At that time
> can we send the value of Foo header stored in cache to upstream backend?
> I tried to achieve this with below code but it could not work.
> proxy_set_header Foo $upstream_http_Foo;
> Would you suggest me how to achieve this or what am I doing wrong here.
This is not something possible.
> On Thu, Mar 20, 2014 at 6:56 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:
> > Hello!
> > On Thu, Mar 20, 2014 at 09:38:40AM +0530, Makailol Charls wrote:
> > > Hi,
> > >
> > > Is there some way to achieve this? I want to pass requests to backend
> > based
> > > on cache status condition.
> > This is not something easily possible, as cache status is only
> > known after we started processing proxy_pass and already know
> > which backend will be used. (Note that by default proxy_cache_key
> > uses $proxy_host, which wouldn't be known otherwise.)
> > If you want to check BYPASS as in your previous message, I would
> > recommend checking relevant conditions from proxy_cache_bypass
> > separately. As a more generic though less effective aproach, an
> > additional proxy layer may be used.
> > --
> > Maxim Dounin
> > http://nginx.org/
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