Recently, Varnish Technical Evangelist Thijs Feryn led a webinar covering Varnish Configuration Language (VCL), the unique programming language that powers all of our software, as well as the popular open source Varnish Cache. For those who weren’t able to attend the webinar, you can watch it here.  

VCL or "Varnish Configuration Language" is an absolutely brilliant idea, which I may have said once or twice already, but it can be a bit much to wrap your head around the first time you approach it, and the built-in VCL notion is an extra curveball. So today, we sit down and tackle this.

We'll avoid examples, long descriptions and overly complex details to focus on the high-level and almost philosophical concepts governing the VCL. Let's do this!

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.