Varnish Cache: What is it and why is it so powerful?

Varnish cache is a known term in the world of Magento, and we make use of it as well. With a good reason, as Varnish is a powerful method to load websites faster.

And we love that at Hipex!

But what isVarnish Cacheexactly?

What is Varnish Cache?

Varnish is a reverse proxy that makes a copy of the page in the memory to serve it out when the page will be re-visited. The copy will be made based on request headers like URL and Request Method. This is known as Full Page Cache.

Varnish Cache ensures pages of webshops do not have to be loaded over again. The performance and page load will benefit a lot from Varnish Cache. And that is exactly what you want: a lightning-fast webshop for all your visitors.

It might be that the definition of Varnish Cache is not 100% clear. We will explain this later on in this article.

Let’s start by explaining how Varnish works.

How does Varnish work?

Varnish Cache stores data in the virtual RAM. Unlike other cache solutions that mainly store elements of a page in the "cache", Varnish Cache saves entire pages.

Varnish is located before PHP (i.e. Magento) and ensures all the requests that have already been dealt with by Magento before and have the same outcome, no longer need to come from Magento but can be served out directly from Varnish.

You mainly configure Varnish via the Varnish Configuration Language (VCL). You write so-called hooks with which external codes are integrated into the application. Then the VCL is converted to C and compiled to the corresponding library.

Advantages of Varnish Cache

The big advantage of Varnish Cache is of course pagespeed. This allows you to book significant performance improvements. But enabling Varnish Cache brings even more benefits.

• Less load of the server, which increases the peak resistance;
• Can be used as a load balancer. Makes static pages faster;
• Configure flexibly via VCL (Varnish Configuration Language);
• Reduce the costs;
• Included in Magento 2 as standard.

Disadvantages of Varnish Cache

Varnish Cache does not only come with advantages. In addition to the many advantages it has, there are also a number of disadvantages. Although these are easy to tackle, or do not outweigh the advantages, it is good to mention them:

• Only to use with Unix operating systems
• No standard integrated SSL Support (At Hipex we offer this)
• The cache can not be updated real-time (There are some out-of-the-box solutions for)

Magento 2 & Varnish

Magento has two default cache extensions:

• The internal cache

  The external cache (varnish)

It is no coincidence that Magento supports Varnish by default. Varnish Cache is installed as an independent component. It serves as an intermediary between the web servers running Magento and the backend memory.

Hipex is entirely responsible for installing Varnish Cache for Magento web shops. Especially for the large websites with many dynamic elements, many visitors and user-specific elements, enabling Varnish can be a complex task.

At the same time, these websites are the ones that need a solution like Varnish the most.

If you want to get started with Varnish yourself and configure it yourself for your own webshop, Magento has made extensive documentation for this.

Varnish HTTP Cache versions

Varnish has a lot of different available versions. The latest version of Varnish is Varnish 6.4.0, released on the 16th of March 2020. This version has many improvements. Of course, all the modifications can be found on GitHub.