Varnish

This module provides integration between your Drupal site and Varnish cache, an advanced and very fast reverse-proxy system. Varnish is a HTTP accelerator that sits in front of your application web-servers and handles serving static files and anonymous page-views for your site.
Varnish is incredibly fast and efficient, but like all caching systems, it needs help to perform invalidations.

This module provides integration with Varnish via it's socket-based administration interface, which allows Drupal to dynamically invalidate cache entries, and also lets you query the Varnish admin interface for status, etc.
As such it requires the PHP sockets extension. If you are unable to enable that, then the Varnish purge module provides an approach using a HTTP client for invalidation.

Drupal 7 version

Is stable, working well, but is minimally maintained.

Drupal 5 and 6 version

Not supported anymore.

Compatibility

At the moment, using Varnish to any effect at all requires Drupal 7 or PressFlow.

We currently support Varnish 2.0, 2.1, 3 and 4 (Drupal 7 only).

Helpful information for those new to Varnish:

• Gregory Chaix's example VCL
• Setting up Varnish and Pressflow Project Mercury Style
• Varnish and Drupal on varnish-cache.org

Also, this module is beginning to implement dynamic cache expiration via the expire module, which will allow for much longer page lifetimes (and thus higher cache hitrates!).

Recommended modules

Modules that should work good in combination with the varnish module.

http://drupal.org/project/cache_actions
https://drupal.org/project/cache_control
http://drupal.org/project/cookie_cache_bypass_adv
http://drupal.org/project/esi
http://drupal.org/project/expire
http://drupal.org/project/purge

Trademark

"Varnish" is a registered trademark used with permission from Varnish Software.