Linux Containers and Virtualization - A kernel perspective

by Shashank Mohan Jain

The book covers internals of virtualization, types of virtualization from vm based to container based virtualization. It also covers other alternate means of virtualization. The book starts from covering basics of virtualization and how its realized in terms of how packet flow happens when a network request is made from a VM. The book then starts to focus on the containerized form of virtualization and how this is realized in the Linux kernel. The different data structures within the Linux Kernel which facilitate this form of virtualization are discussed . It entails the 3 pillars of containerization namely namespaces, cgroups and layered filesystem. The book goes into details of how namespaces are realized within the linux kernel and which data structures help in providing this isolation. Then the book talks about cgroups are realized within kernel with example of couple of cgroup controllers. It covers how layered filessystem is created and whats its purpose with examples. Once the conceptual understanding is developed, the book moves on to explanation of how one can create their own container. The book then covers in depth with examples on how various namespaces are realized with explanation of individual namespaces like pid, usernamespace and in particular the network namespace. Finally a user can see his own container working with all the namespaces and packet flow happening between host and container. The book finally covers code to create own cgroups within the container and takes some example to apply cgroups within your own container runtime. The basic theme of the book is to give the user an idea of how virtualization is being done in cloud today and what all options exist for the same. The book then details out how container eco systems work today and finally peels the different layers of containers and enables user to create his own container runtime like Docker.

149 pages, Kindle Edition

Published July 16, 2019

Reviews

[Alanna · Rating 3 out of 5]

Picked this up from a recent Humble Bundle and looked through it as a refresher. I think someone reading this would likely have some sort of related background, and although the author makes a valiant effort at the beginning to briefly abstract the concept of virtualization to ease into the subject but quickly ramps up. The rest of the text follows a pattern of either being too simplified or putting in instructions and details with no prior explanation to clarify what is being described.

Definitely good for someone who wants a refresher but not a cohesive explanation of the topic.