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 ​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
example.org	209.51.180.234
www.example.org	209.51.180.234
example.com	209.51.180.234
www.example.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 ​Pressflow distribution.
• Drupal 7: According to ​Propeller-heads Unite!, you may need to add the following to your settings.php file:

  # Tell Drupal it's behind a proxy
  $conf['reverse_proxy'] = TRUE;
  # Tell Drupal what addresses the proxy server(s) use
  $conf['reverse_proxy_addresses'] = array('209.51.180.234');
  

Additionally, the ​Drupal varnish plugin provides added functionality.

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.

Testing

To see if Varnish is working, type your domain into the ​Is Varnish Working site.

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.