5 Don'ts When Caching with Varnish

Over time, the most popular content we’ve created relates to hands-on Varnish use and relevant dos and don’ts. Naturally, we continue to create more content about this because our raison d’être is to help Varnish users get the maximum performance and efficiency they can from their Varnish setups.

Let’s get down to business.

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10/19/20 6:57 PM
by Arianna Aondio

Hit-for-Miss AND why a NULL TTL is bad for you

Varnish is a caching server, and a great one at that, that much we already know. But what about the content you don't want to cache? For example, those shopping cart requests and other completely uncacheable API calls?

We can of course handle it, but we've got to be wary of the sirens of the cargo cult because you will often see something like this on the internet:

sub vcl_backend_response {
# check if the backend response header named
# "cache-control" contains the word "private"
if (beresp.http.cache-control ~ "private") {
# if so, don't cache by limiting the Time-To-Live
# period to 0 second
set beresp.ttl = 0s;
}
}

This is both pretty intuitive, and also very wrong. In this post, we'll explore why it's a bad idea, how to do better, and along the way, we'll try to shine some light on a couple of lesser known features of Varnish.

 

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10/15/20 4:12 PM
by Guillaume Quintard

Ending the pipe dream: when to use pipe in Varnish

As you may know, part of my job consists of helping Varnish users, both customers and community users (join us on IRC!), often looking at their VCL and see if there's anything wrong. And sometimes, there is. After all, VCL is a programming language and mistakes happen. However, one point stands out as being badly understood, and I feel it deserves a short blog post to set the record straight.

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3/14/18 2:00 PM
by Guillaume Quintard

Varnish Configuration Language: VCL snippets

The Varnish Configuration Language (VCL) is a small domain-specific language designed to be used to define request handling within Varnish. It is extremely flexible and allows you to let Varnish do exactly whatever you want or need it to do.

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3/8/17 1:30 PM
by Arianna Aondio

Varnish Software Blog

The Varnish blog is where our team writes about all things related to Varnish Cache and Varnish Software...or simply vents.

 

 
 

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