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Building Blocks of Containers
The Linux Foundation | 30 May 2017
This article series previews the new Containers Fundamentals training course from The Linux Foundation, which is designed for those who are new to container technologies. In previous excerpts, we talked about what containers are and what they’re not and explained a little of their history. In this last post of the series, we will look at the building blocks for containers, specifically, namespaces, control groups, and UnionFS.
Namespace is a feature of the Linux kernel, which isolates and virtualizes system resources for a process, so that each process gets its own resource, like its own IP address, hostname, etc. System resources that can be virtualized are: mount [mnt], process ID [PID], network [net], Interprocess Communication [IPC], hostnames [UTS], and users [User IDs].
Using the namespace feature of the Linux kernel, we can isolate one process from another. The container is nothing but a process for the kernel, so we isolate each container using different namespaces.
Another important feature that enables containerization is control groups. With control groups, we can limit, account, and isolate the resource users like CPU, memory, disk, network, etc. And, with UnionFS, we can transparently overlay two or more directories and implement a layered approach for containers.
You can get more details in the sample course video below, presented by Neependra Khare (@neependra), Founder and Principal Consultant at CloudYuga, Docker Captain, and author of the Docker Cookbook.
Want to learn more? Access all the free sample chapter videos now!