Hi Reza,
Yes we are. Here's the default we apply. Those two subs are called in order in
vcl_backend_response:
/* REMOVE CACHE-CONTROL AND SURROGATE-CONTROL FROM BACKEND *
***********************************************************/
sub stm_backend_resp_unset_cache_control_headers {
unset beresp.http.Surrogate-Control;
unset beresp.http.Cache-Control;
unset beresp.http.Expires;
}
/* DEFAULT ALL TO: TTL 30MIN + GRACE 15MIN *
*******************************************/
sub stm_backend_resp_expiration_default {
set beresp.ttl = 30m;
set beresp.grace = 15m;
}
That doesn't seem to have any impact when the backend responds with a
Cache-Control: max-age=0 header.
Any idea?
De : Reza Naghibi [mailto:[email protected]]
Envoyé : jeudi 20 juillet 2017 13:58
À : Girouard, Yanick <[email protected]>
Cc : [email protected]
Objet : Re: Varnish and max-age=0
The TTL is calculated before entering vcl_backend_response. So eventhough you
unset the Cache-Control header, the value of TTL will be calculated based on
it. Are you setting a new value for beresp.ttl? You need to do that:
sub vcl_backend_response
{
unset beresp.http.Cache-Control;
set beresp.ttl = 120s;
}
--
Reza Naghibi
Varnish Software
On Thu, Jul 20, 2017 at 1:44 PM, Girouard, Yanick
<[email protected]<mailto:[email protected]>> wrote:
Hi,
We use Varnish to cache for multiple backends and need Varnish to always
control what is cached despite what backends could respond. In other words,
even if a backend sets Cache-Control headers to never cache its pages, we still
want Varnish to cache them based on defined rules (i.e. certain URL patterns or
hosts have different TTLs).
We have recently realized that one of our backend always set the following
header: Cache-Control: max-age=0, private, must-revalidate
Our VCL unsets the Cache-Control header in vcl_backend_response and sets its
own before delivering. By unsetting the Cache-Control header in
vcl_backend_response I would expect Varnish to ignore the max-age=0 value and
still cache the page as per our other rules, but it seems that the second it
sees max-age=0 in the response header, that it makrs the object as not
cacheable.
Other than by changing the backend's response to never set max-age=0, is there
a way to force Varnish to cach pages even if it returned max-age=0?
Is this even by design or is it a bug?
Thanks,
Yanick Girouard
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