= Shared Varnish Caching =
If you find that your site runs slowly and you've turned on all the CMS specific caching features available to you, it might be time to use our shared [https://www.varnish-cache.org/about varnish server].  Varnish helps manage higher traffic websites by creating a cache of all the previous page loads and serving them up with a minimal amount of processing.  In order to hook into our shared varnish instance, you'll need to make some changes to your DNS entries, and a support team member will need to add a file to our varnish server (currently dolores.mayfirst.org).

 == Changing DNS Entries ==
Visit the control panel and the hosting order that should use varnish caching.  Change the DNS entry for the appropriate domains.  For example, you might want 

|| '''Domain Name''' || '''IP Address''' 
|| myexample.org || 209.51.180.234
|| www.myexample.org || 209.51.180.234
|| myexample.com || 209.51.180.234
|| www.myexample.com || 209.51.180.234
|| '''example.mayfirst.org''' || '''doesn't change'''

Notice that the last entry example.mayfirst.org did not change.  This domain can serve as a direct link to the server in case anything goes awry. 

 == Modify Your Config Files ==
Some CMS's require you to modify your configuration files.  You should check to make sure you have the correct configurations set.

 === For Mediawiki ===
In your LocalSettings.php, you'll need to add the following: 
{{{
$wgUseSquid = true;
$wgSquidServers = array('209.51.180.234:80');
}}}

 === For Drupal ===
 * Drupal 6 requires the [http://pressflow.org/ Pressflow] distribution.
 * Drupal 7 should work fine using the standard MF/PL web app.

 === Wordpress ===
You shouldn't need to take any special steps for wordpress caching.  Though please make sure to turn off W3 Total Cache before using our shared varnish server.

 == Support Team ==
Our current varnish server is dolores.  You'll need to make the following configuration changes for each new hosting order. 

 * Create a new vcl file for the domain, i.e. /etc/varnish/vhosts/domain-name.vcl
 * Copy the format of a current vcl file, depending on the CMS.
 * Add an include line in /etc/varnish/vhosts/vhosts-list.vcl for the file you created above.
 * run /etc/init.d/varnish reload

'''NOTE:''' The above instructions should ultimately become a part of puppet or red.