18 Mar 2016
In my last miniseries, we gave an overview of CoreOS. In this miniseries, I want to take a look at Docker. In this post we’ll look at why it’s special and how it’s built. We’ll start at the beginning, so don’t worry if you’re totally new to this.
Docker is an open source project that makes easier packaging of applications inside containers by providing an additional layer of abstraction and automation of operating-system-level virtualization on Linux.
Containers themselves are just an abstraction over Linux cgroups, which are a lower level kernel construct for jailing and limiting the resources of a process and its children.
Docker was using LinuX Containers (LXC) in the beginning, but then switched to runC, formerly known as libcontainer. runC runs in the same operating system as its host. This allows it to share a lot of the host operating system resources, such as RAM, CPU, networking, and so on.