[squid-users] icap result caching in squid

Amos Jeffries squid3 at treenet.co.nz
Wed Dec 4 05:26:28 UTC 2019

On 4/12/19 6:05 am, Darren Breeze wrote:
> Hi Amos
> The Icap service is doing redirects based on client permissions (that may change). What I am doing is just setting the Expires value in the RESP_MOD response when I return a 307 redirect so I can control how long the caches (both Squid and the browser) hang on to it.

In that case you should be using Cache-Control:max-age=NN instead where
the NN being your desired TTL in seconds. This is a *lot* simpler and
faster to deliver than calculating the timestamps needed for valid
Expires header.

Also, are you aware that current Squid versions can generate redirects
(custom headers included) based on output from an external_acl_type helper?
 A helper to lookup your permissions system plus a few extra squid.conf
settings would be a lot simpler in terms of traffic processing and
bandwidth consumption than sending everything through an external ICAP


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