This is where containers come into thepicture. Containers solve the matrix of hell without involving a heavy guest OS layer between them. Instead, they isolate the application runtime and dependencies by encapsulating them to create an abstraction called containers. Now, you have multiple containers that run on a single OS. Numerous applications running on containers can share the same infrastructure. As a result, they do not waste your computing resources. You also do not have to worry about application libraries and dependencies as they are isolated from other applications – a win-win situation for everyone!
Containers run on container runtimes. While Docker is the most popular and more or less the de facto container runtime, other options are available on the market, such as Rkt and Containerd. They all use the same Linux kernel cgroups feature, whose basis comes from the combined efforts of Google, IBM, OpenVZ, and SGI to embed OpenVZ into the main Linux kernel. OpenVZ was an early attempt at implementing features to provide virtual environments within a Linux kernel without using a guest OS layer, which we now call containers.
It works on my machine
You might have heard this phrase many times in your career. It is a typical situation where you have erratic developers worrying your test team with “But, it works on my machine” answers and your testing team responding with “We are not going to deliver your machine to the client.” Containers use the Build once, run anywhere and the Package once, deploy anywhere concepts and solve the It works on my machine syndrome. As containers need a container runtime, they can run on any machine inthe same way. A standardized setup for applications also means that the sysadmin’s job is reduced to just taking care of the container runtime and servers and delegating the application’s responsibilities to the development team. This reduces the admin overhead from software delivery, and software development teams can now spearhead development without many external dependencies – a great power indeed! Now, let’s look at how containers are designed to do that.
