Preventing Caching in Varnish Based on Backend Response Header

[Uday Kumar]

Noted.

Thanks for suggestion

*Thanks & Regards,*
*Uday Kumar*


On Tue, Jun 11, 2024 at 10:35 PM Guillaume Quintard <
guillaume.quintard at gmail.com> wrote:

> Hi,
>
> Don't worry too much about it. Uncacheable objects take a minimal amount
> of space in the cache, and if an object suddenly becomes cacheable, you can
> insert it in the cache, pushing the uncacheable version out.
>
> I'd say keep 24 hours and worry about big stuff :-)
>
> Cheers,
>
> --
> Guillaume Quintard
>
>
> On Tue, Jun 11, 2024 at 4:22 AM Uday Kumar <uday.polu at indiamart.com>
> wrote:
>
>> May I know if there is any way to find the best possible TTL?
>> I meant to ask for uncacheable objects
>>
>> *Thanks & Regards,*
>> *Uday Kumar*
>>
>>
>> On Tue, Jun 11, 2024 at 4:11 PM Uday Kumar <uday.polu at indiamart.com>
>> wrote:
>>
>>> Hello Guillaume,
>>> We have made required changes at our end, but we have doubt on giving
>>> suitable TTL for uncacheable objects
>>>
>>> if (beresp.http.Cache-Control ~ "no-cache") {
>>>         set beresp.ttl = *doubt*;
>>>         set beresp.uncacheable = true;
>>> }
>>>
>>> FYI;
>>> we have ttl of 24hrs for normal objects which are cacheable
>>>
>>> May I know if there is any way to find the best possible TTL?
>>>
>>> *Thanks & Regards,*
>>> *Uday Kumar*
>>>
>>>
>>> On Tue, May 28, 2024 at 7:07 PM Uday Kumar <uday.polu at indiamart.com>
>>> wrote:
>>>
>>>> Hello Guillaume,
>>>> Great to know about this, it should work for us!
>>>> will check this out
>>>>
>>>> *Thanks & Regards,*
>>>> *Uday Kumar*
>>>>
>>>>
>>>> On Tue, May 28, 2024 at 5:53 PM Guillaume Quintard <
>>>> guillaume.quintard at gmail.com> wrote:
>>>>
>>>>> Hi Uday,
>>>>>
>>>>> Sure, the classic practice will do nicely:
>>>>>
>>>>> sub vcl_backend_response {
>>>>>     if (beresp.http.that-specific-header) {
>>>>>         # TTL should match the time during which that header is
>>>>> unlikely to change
>>>>>         # do NOT set it to 0s or less (
>>>>> https://info.varnish-software.com/blog/hit-for-miss-and-why-a-null-ttl-is-bad-for-you
>>>>> )
>>>>>         set beresp.ttl = 2m;
>>>>>         set beresp.uncacheable = true;
>>>>>         return (deliver);
>>>>>     }
>>>>> }
>>>>>
>>>>> The main trick here is beresp.uncacheable, you do not have to return
>>>>> immediately if you still have modifications/checks to do on that response.
>>>>>
>>>>> Would that work for you?
>>>>>
>>>>> --
>>>>> Guillaume Quintard
>>>>>
>>>>>
>>>>> On Tue, May 28, 2024 at 4:55 AM Uday Kumar <uday.polu at indiamart.com>
>>>>> wrote:
>>>>>
>>>>>> Hello all,
>>>>>>
>>>>>> We need to prevent caching in Varnish based on a specific header from
>>>>>> the backend.
>>>>>>
>>>>>> Could you please suggest the best approach to achieve this?
>>>>>>
>>>>>>
>>>>>> *Thanks & Regards,*
>>>>>> *Uday Kumar*
>>>>>> _______________________________________________
>>>>>> varnish-misc mailing list
>>>>>> varnish-misc at varnish-cache.org
>>>>>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>>>>>>
>>>>>
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