[squid-users] Re: http 302 status and storeid: infinite loop problem

From: Niki Gorchilov <niki_at_gorchilov.com>
Date: Tue, 8 Oct 2013 17:28:59 +0300

After a little bit of additional thinking, I believe in case of
store_id rewritten request, we shall ONLY cache response with status
code 200. In case of any other response code we have to leave the
end-user application to find it's way to recover from it, including
requesting the same object from other nodes.

On Tue, Oct 8, 2013 at 5:18 PM, Niki Gorchilov <niki_at_gorchilov.com> wrote:
> Hi there.
> Started playing with Squid store_id feature (thanks Eliezer for
> the implementation) and discovered an unresolvable issue, due to the
> caching of 302 results (I know it's happening when only Expires header
> is present, but anyway).
> Imagine the following scenario (that happens quite often): an CDN node
> currently offline for maintenance, redirecting all the traffic to
> another node with 302 Moved Temporary response.
> As the first node's url has been normalized by the store_id helper,
> the response gets cached under the squid.internal url.
> Now, when Squid follows the redirect to the new CDN node, the store_id
> helper returns the same normalized url (as intended :-), so the cached
> 302 result pops up again, forcing squid to reconnect this same node...
> Boom! Infinite loop
> Any suggestions how to avoid this loop? Tried playing with http_status
> acl but discovered it's not applicable in this scenario (as discussed
> by Amos and Eliezer more than a year ago).
> Without a method to disable caching of 30x results from squid.conf
> store_id feature is not usable, IMHO!
> Best,
> Niki
Received on Tue Oct 08 2013 - 14:29:47 MDT

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