Many people have heard of the container for a while or even use it every day. However, a question like "what is container" or "how container works" might still rise.
In this post, we will deep dive into the container.
Before container era, we usually use visualization technology to limit and control system resources for the applications. However, it creates too much overhead on the physical machine. And thus, container as a lightweight solution emerged.
Docker is the dominant container technology in the industry. Check Docker Overview for more information.
CoreOS rkt is yet another application container engine. The advantage of rkt is its cloud-native nature. Check A security-minded, standards-based container engine: rkt.
LXC and LXD is system container engine. It offers an environment as close as possible as the one you'd get from a VM but without the overhead that comes with running a separate kernel and simulating all the hardware. Check linuxcontainer.org.
The Open Container Initiative or OCI develops specifications for standards on Operating System process and application containers. It defines two specs: the Runtime Specification and the Image Specification.
Bocker is a container engine implemented in 100 lines of Bash code. It's mainly for education. Check p8952/bocker.
We will demonstrate that container technology is not shiny new thing. It provides so much values by simply combining several old technologies: namespace, cgroups, and union filesystem.
A container is merely an OS process, except that it's being isolated, secured, and limited. All values added to the process make the container the dominant technology in the cloud era.