Website Performance and Security Blog

How to Install Varnish Cache

varnish cache tutorial

Varnish Cache has quickly grown to be a popular reverse proxy software for accelerating HTTP requests and caching static and dynamic content. It’s an incredibly powerful way to speed up websites, increase scalability, and reduce server costs. Getting started, however, can be a bit of a headache. Before you dive into the fundamentals of VCL let’s take a quick look at everything you need to know about installing Varnish Cache.

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Debugging Varnish VCL

Varnish Cache’s Configuration Language (VCL) can be very approachable to get started with basic caching behaviour for your website. However, once you start to leverage the power of VCL to achieve the best possible performance for your site, you can find yourself in a situation where some HTTP requests don’t appear to be behaving how you expect. Varnish has some great tools to help you troubleshoot.

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Varnish 5.2 Already Available on

Varnish Cache released their latest 5.2 version late last week and it is already available on’s globally distributed Application Edge.

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Announcing Virtual Waiting Room

waiting room is pleased to announce another feature to help websites stay online when extreme traffic peaks arrive. A Virtual Waiting Room can ensure that your website stays up and serving customers when an extreme traffic event would otherwise have caused a complete outage.

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Early TLS deprecation

Since before PCI DSS 3.2 was published, has provided delivery infrastructure with early TLS protocol versions disabled to allow customers to adopt the PCI requirements ahead of the June 2018 deadline. For many other customers though, disabling early TLS would have prevented too many visitors from being able to access, or complete transactions, on their websites.

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Tips to Make Sure Your DNS Registration Doesn't Expire

ajax calls

During my time at I have seen the websites of our customers and our partners go offline due to a seemingly innocuous administration error: failing to renew their domain name registration on time. This issue was recently brought to the forefront recently when the popular marketing tool Marketo failed to renew their domain name, and were shut out of their system for several hours.

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What is An AJAX Call?

ajax calls

AJAX calls, which stand for Asynchronous JavaScript And XML, are becoming more popular as web applications look to bring in personalized items dynamically. AJAX calls are one method to load personalized content separately from the rest of the HTML document, which allows for the full HTML document to be cached, improving back end load time.

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How to Prepare Your Ecommerce Site for the Holiday Season

website performance holiday

Each year the holiday season seems to roll around more quickly, with Thanksgiving decorations popping up before Halloween has concluded and winter-themed decorations and merchandise appearing in stores mid-September. For retailers, holiday sales dominate promotions beginning in mid-November and go all the way through post-season blowouts in January.

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How Page Load Time Affects Bounce Rate and Page Views

page speed bounce rate

It’s become common knowledge that the speed at which pages load is a crucial part of user experience, and recently page speed has become more and more important in other areas - Google’s search engine ranks pages based on page load time (specifically, time to first byte), and Facebook has announced that it will prioritize links that load quickly in its newsfeed over those that are slow to load, saying “We’ve heard from people that it’s frustrating to click on a link that leads to a slow-loading webpage. In fact, even more broadly on the internet, we’ve found that when people have to wait for a site to load for too long, they abandon what they were clicking on all together.”

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Troubleshooting Varnish Cache 503 Guru Meditation Error

varnish cache server error

If you use Varnish Cache on your website or are visiting a website that caches content with Varnish, chances are at some point you will come across the Varnish server error: Error 503 Service Unavailable / Guru Meditation with an XID number. A 503 error means that the web server trying to be reached is unavailable - this could be because it is overloaded, down for maintenence, or not fully functional for another reason.

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