Varnish Foo is the ultimate Varnish Cache book out there. Or it will be, when it's done.
This book is not done yet. The individual chapters are meant to stand well on their own, but many chapters are yet to be written and the content is likely to evolve over time.
I am very interested in any and all feedback, from pure spelling mistakes to factual errors or whether the book flows well or not.
Chapter 1 through 3 stand well as they are, all though they might need some updates here and there.
I am currently progressing through VCL.
Chapter 4, introduction to VCL, can be used as a reference as it is, but I have not done a thorough review of it yet from a pedagogical point of view. I expect some parts to require changes to be truly good.
Chapter 5 is currently being developed from scratch. Much has changed since I was at my peak in the Varnish community, so I intend to update my own knowledge throughout the development of that chapter (and further chapters). I do have some really good bits in store for you all, though.
Basically: Read chapter 1 through 4 as "true", but don't assume chapter 5 represents current best practices until further notice.