High Performance Drupal

Chapter 19. Reverse Proxies and Content Delivery Networks

We’ve discussed a number of ways to speed up Drupal sites by improving code, optimizing infrastructure, and speeding up database queries. These changes can make a huge difference in website performance, but they can only go so far. Site performance can be improved even further by caching content before requests even reach Apache (and Drupal, PHP, or MySQL). Reverse proxies provide a way to do just that—cache static items such as images, JavaScript, and CSS, and potentially even full pages—and serve those items in a fraction of the time it would take if the request had go into Apache, PHP, and MySQL. This chapter focuses on reverse proxies with built-in caches, also referred to as web accelerators.

Content delivery networks (CDNs) take the idea of a reverse proxy a step further by moving cached content physically closer to website visitors. In addition to offloading network traffic from your infrastructure, this also makes your site seem much faster to visitors by reducing their network latency.

Using a Reverse Proxy with Drupal

When implementing a reverse proxy cache in front of your web servers, there are many options to consider. First up is which reverse proxy to use. Varnish has become very popular in recent years and its configuration language is extremely powerful, allowing for very specific caching configurations. Varnish has generally become accepted by the Drupal community as the reverse proxy of choice, so we’ll concentrate ...