[squid-users] RE: Clearing the Squid cache or disabling caching d uring certain periods

Chris Robertson wrote:
> jennyw wrote:
>> Chris Robertson wrote:

>>>> acl maint_time time 04:00-05:00
>>>> acl maint_pages dstdomain .my.server
>>>> no_cache deny maint_time maint_pages

>> Hmmm ... I tried using this:
>>
>> acl MAINT time 12:32-12:35
>> no_cache deny MAINT
>>
>> But during the time specified, when I hit pages I still got this header:
>>
>> X-Cache: HIT from squid

> To the best of my knowledge (and I imagine I'll be corrected if wrong)
> Squid completely ignores acls for cached content.

That would be a very broken and stupid behavior, and is not the case with
Squid. For example, consider a proxy that uses authentication.

If Squid doesn't bother to check ACLs for cached content, you would see no
authentication information for any TCP_HIT entries, because Squid would not
process the ACLs and therefore would not request authentication information
from the client.

However, you do see the authentication information for TCP_HIT entries in
access.log, therefore Squid still checks the ACLs for cached content.

Another way to tell would be to turn up the debugging for access controls,
then look at the data in cache.log for requested content that is cached.

> Similarly, during the MAINT time listed above (12:32-12:35) no NEW pages
> will be cached, but any pages currently in cache will be served.

This is entirely possible - provided that Squid has no way to validate the
freshness of the content, and it has not otherwise been marked as stale
(which seems to be the issue this thread is attempting to resolve).

Adam
Received on Sat Feb 12 2005 - 13:11:01 MST