Re: [squid-users] refresh_pattern based on acl

 On Wed, 02 Mar 2011 16:11:55 +0200, Leon Volfson wrote:
> Hi,
>
> I have a few squid servers in front of web servers (accelerator
> setup).
> Since the website is very dynamic, I had to turn off the client
> refresh action:
>
> refresh_pattern -i ^http://www.website.com 14400 80% 43200
> ignore-reload
>
> but then I got the problem: some files that have a 7 days caching
> time - I have no way of refreshing them if I modify the file on the
> webserver.

 NP: The safe way to save on traffic while obeying the standard is
 "reload-into-ims". Which converts a full force-reload into an efficient
 revalidation.
  If the server app fails to perform revalidation then one of efficiency
 or reliability are screwed.

 Client refresh is not that commonly used by modern software. You should
 not need this unless you still have a large IE5/IE6 visitor base or are
 receiving peer-relayed requests from squid-2.5/2.6 peers.

>
> To make it clearer, I have some .js or .css file which has a max-age
> of 7 days. It's cached by squid and everything's great.
> After a day I modify the file, but the squid keeps serving the old
> version.
>
> What are the possible solutions in these situations (besides
> shortening the max-age)?

 For this refresh_pattern to have any effect the Cache-Control: and
 Expires: headers must be missing or unusable from the reply object squid
 receives from the server. max-age control being too high with no
 last-modified header makes more sense as the core problem.

 Making those .js and .css non-dynamic would go a great way towards
 stability and let the server present last-modified headers and correct
 IMS handling. Otherwise implement some of it yourself in the scripts
 which server them up.

>
> Is there any way to have another refresh_pattern rule based on my
> local IP (acl)?

 No. refresh_pattern is a URL-staleness estimate calculation. The only
 relevant things are the URL and some HTTP headers.

 You could work around this using squid-3.1 with the public http_port
 having "ignore-cc" to disable client specs (instead of the overly broad
 refresh pattern) and do admin requests with reload through a separate
 forward-proxy port.

 Amos
Received on Thu Mar 03 2011 - 00:19:28 MST