A must-read if you're into containers, Docker, Kubernetes or service meshes.
This book is not an introduction, but it's all about looking under the hood: how do the containers actually work, what does truly separate the running processes, what are the typical vector attacks for containers, what are the good and bad security practices (& I don't mean the obvious ones!). What's more, it's the only book on this particular topic I know - this strongly reduces the competition :)
The best chapters? Definitely 3 (cgroups) & 4 (container isolation on a system level). Very container-specific, very low level - yet absolutely crucial to have a full understanding of what a container truly is. Pure gold.
Strongly recommended.