Bazel is a Google-derived build system with some interesting properties but a steep learning curve. In hopes of getting up that curve, I bought a few books recenly, among them Bazel in Depth: Definitive Reference for Developers and Engineers by Richard Johnson. I thought I might share my reactions in case they are helpful.
tl;dr: don't bother.
The text is meandering and repetitive. Every chapter has at least one multi-page superlative-laden discourse on hermetic builds. The chapter on dependency management spends many pages talking about lockfiles (which Bazel doesn't use).
The text rarely gets into details -- it is definitively not a reference, but more of a verbose treatise on build systems as a general concept.
When it does get into details, they're generally wrong. For example, some of the starlark examples use enddef to end a function definition. That's not a thing. The book mentions the @rule decorator for rule definitions. Nope. Apparently list comprehensions aren't allowed? They are, and are quite common. Apparently while is allowed? No, very much not.
