Preventing Caching in Varnish Based on Backend Response Header

[Guillaume Quintard]

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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