SearchCongratulations! You’re at the end of chapter 4, in which we covered the ins and outs of VCL.
At this point, you should be comfortable with VCL. You should be able to understand its syntax, you should know about the subroutines, the return statements, and the variables.
The main objective is to understand how Varnish leverages the finite state machine, how the built-in VCL is used to control states and transitions, and how you can extend that behavior with VCL.
Although there’s educational value to this chapter, you cannot consider it as documentation. If you need documentation for VCL, you’ll find it at http://varnish-cache.org/docs/6.0/reference/vcl.html#varnish-configuration-language.
Every chapter from now on will use VCL, so be ready to apply what you learned.
Let’s get ready for chapter 5 where we’ll explain what VMODs are, which ones are shipped by default, and how you can use them. We’ll even show you how to write your own VMODs.