Containerization is a form of virtualized operating system developed as a response to the many problems of hardware-level virtualization. Because the latter runs a full-blown guest operating system, it is very resource-intensive and incurs a significant amount of overhead, but containerization is much lighter. Since the containers share the host machine’s kernel, the resources are not wasted on running separate operating system tasks. This allows for a much quicker and lightweight deployment of applications.
Docker is a containerization software that is used for automating the deployment and management of applications within an isolated environment. This software allows us to “pack” and ship an application, along with all of its needed files, libraries, and dependencies, into a “docker container“. That container can then be easily ported to any Linux system that contain cgroups support within the kernel, and provides a container management environment. Docker is one of several containerization implementations (not to be confused with virtualization) based on this cgroups mechanisms built into the Linux kernel.
Before we begin, let’s describe what Docker is. Docker is a set of virtualization tools that allows us to create, test, and deploy containerized applications quickly and easily on a dedicated server. It has become very popular and used almost everywhere in our daily lives. Thanks to containerization, we can quickly launch applications on different cloud platforms utilizing small bundles which contain all the needed packages, libraries and configuration file to run an application. These docker packages communicate via established network channels.