I agree that the documentation available is a bit diversified but there’s quite alot of it. Maybe that’s part of the problem?

My primary source for VCL documentation is the vcl manual that comes with Varnish, which should contain all VCL constructs and be up to date. Some times it gets left behind for a few commits, but it’s usually pretty up to date. The Wiki has a few examples and stubs, some of these stubs might be a bit old, if you spot such a page, feel free to fix it or just drop by #varnish at irc.linpro.no or drop us an e-mail at the public mailinglists and we’ll sort it out.

As for the flexibility of VCL what you have to remember is that VCL isn’t meant to be a fully fledged programming language, and if you compare it to such a language, it will almost always fall short. However, VCL itself is rarely a hindrance. One of our main policies while developing Varnish is to leave policy decisions to VCL, and I belive we’ve been able to do that quite well so far.

And just in case you really want something that VCL can’t do, you can always resort to inline C code.

However, mastery of regular expressions makes a significant difference when it comes to writing VCL, and it’s not necessarily easy.

As for your examples, they are definitely useful. I’ll say they are typical examples of things one can expect to do when working with Varnish.