Re: [squid-users] how to use parent cache_peer with url_rewriter working on it

On 20/04/2012 7:01 p.m., x-man wrote:
> Hello there,
>
> I am planning for squid implementation which consists of one main squid that
> will server all the web except the video sites and second squidbox that
> will only deal with the video content.
>
> As I know I have to use the cache_peer directive to tell the main squid that
> it has to ask the video squid about a content (it will be based on ACLs).

No cache_peer tells Squid how to setup TCP connections to a peer. That
is all.

cache_peer_access "will be" is what tells Squid *which* requests to pass
there. The problem you are describing can be the result of not having
those ACLs present. The child Squid only re-tries alternative paths if
the parent proxy fails to supply a response for the client (ie link
outages get routed around).

>
> The problem that I see is that the second squid who is using url_rewriter
> and local apache script to cache and deliver the video content will always
> reply with cache miss, to the main squid, because for the squid this is not
> cached content - as it is maintained by the url_rewriter and apache php
> script - then the main squid will deliver the content from the internet.

URL re-writer does not "maintain" any part of HTTP. Its sole purpose is
to alter the URL for a request before that request gets serviced.

What does Apache have to do with a two-Squid peering setup?

>
> Someone can suggest workaround for this?

Only certain specific types of HTTP "route" failure status causes the
main Squid to retry like you describe. You need the URL-rewriter NOT to
cause 4xx/5xx errros.

You can disable the retries by using never_direct with exactly the same
ACL rules used in cache_peer_access to select the parent cache. What
that will do is cause the 4xx/5xx errors caused by your re-writer to be
passed to be the client instead of the real video found and fetched.

Amos
Received on Fri Apr 20 2012 - 12:59:36 MDT