RE: [squid-users] How to not cache a site?

It took me sometime to find this email until a friend pointed it out.
You brought up the point that we have been trying to solve by not
caching the site.

Here is the full story. There is a site behind our Reverse Proxy that
keeps on getting funky due to missing icons and some pages that does not
follow the formatting. Looking into this issue, we realized that even
if we configured our HTTP Headers not to cache this site, I still find
instances of that site in the cache during purging. This is what
started this post.

We have compiled our Apache to use mod_auth_session to assist in
security of the site.

What you have provided below seems to have pointed us to resolving this
issue.

"The redirection just has a "Cache-Control: max-age=0", which allows the

cache to store the response, and just requires that it be revalidated
(which is done as evidenced by the TCP_REFRESH_HIT in the Squid log)."

It seems that when the responses got stored, the authentication gets
funky and in effect some objects referenced in the page cannot be
access. We will modify our mod_auth_session code to avoid this
condition. If neither the recoding of mod_auth_session nor adding the
"cache deny" directives does work, I will update this post.

Thank you so much, Chris.

Regards,
Jerome

-----Original Message-----
From: crobertson_at_gci.net [mailto:crobertson_at_gci.net]
Sent: Tuesday, June 10, 2008 1:12 PM
To: squid-users_at_squid-cache.org
Subject: Re: [squid-users] How to not cache a site?

Jerome Yanga wrote:
> Resending as I had received a failure notice message.
>
> I do not think that the refresh_pattern is even setup as they are all
> commented out.
>
> # grep refresh_pattern /etc/squid/squid.conf
> # refresh_pattern regex min percent max
> #refresh_pattern -i \.js$ 0 0% 1
> #refresh_pattern -i \.css$ 0 10% 30
> #refresh_pattern . 0 20% 4320
>
> Attached is a zipped http header log captured using Live HTTP Headers.
>
> Regards,
> Jerome
>

Sample squid log entry from the zip file (without cookies) for
reference:

------------------------
TCP_REFRESH_HIT:FIRST_UP_PARENT 10.11.12.13 10.10.10.10 - -
[06/Jun/2008:21:42:52 +0000] "GET
http://site_address.com/help/chr_ind_on.gif HTTP/1.1" 302 830
"http://site_address.com/help/whskin_tbars.htm" "Mozilla/5.0 (Windows;
U; Windows NT 5.1; en-US; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14"
------------------------

There were no associated HTTP headers for this object
(http://site_address.com/help/chr_ind_on.gif)*, but here is another
request that also resulted in a 302 (Moved Temporarily):

------------------------
GET /help/chr_back.gif HTTP/1.1
Host: site_address.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.14)

Gecko/20080404 Firefox/2.0.0.14
Accept: image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://site_address.com/help/whskin_tbars.htm
Cookie: [removed]

HTTP/1.x 302 Moved Temporarily
Date: Thu, 05 Jun 2008 23:40:54 GMT
Location:
http://site_address.com/gateway/index.cfm?fa=login&returnURL=http%3A%2F%
2Fsite_address%2Ecom%2Fhelp%2FFchr%5Fback%2Egif
Cache-Control: max-age=0
Expires: Thu, 05 Jun 2008 23:40:54 GMT
Content-Length: 422
Content-Type: text/html; charset=iso-8859-1
Connection: keep-alive
------------------------

The redirection just has a "Cache-Control: max-age=0", which allows the
cache to store the response, and just requires that it be revalidated
(which is done as evidenced by the TCP_REFRESH_HIT in the Squid log).

So, I'm still not seeing anything being cached against the server's
request. Try tailing the access log and grep for " 200 " and "HIT"**
(note the spaces on either end of the 200). That should show any
objects (as opposed to redirects or errors) that are served from cache.

Chris

* The other URL (http://site_address.com/help/whskin_tbars.htm) it the
referrer.
** tail -f /cache/logs/access.log | egrep "10.10.10.10.* 200 .*HIT"
Received on Wed Jun 11 2008 - 17:09:45 MDT