Containerization, also known as container stuffing or container loading, is a relatively new term in software development. With various deployment environments coming up, especially the ones connected to the cloud computing, it has gained vast popularity.

In this article, we explain why virtualization appeared on the level of operating systems, how it works and what advantages it gives to developers and business.

What is containerization?

Containerization is deploying software together with all the necessary components: code, libraries, frameworks etc., in a way that they are isolated in their own container.

Take traditional software development methods — this process takes place in a particular computing environment. If it is moved to another place, for instance, from PC to the cloud, or from Linux to Windows, a set of errors and bugs could pop up. With the help of containerization, one can unite all software elements into a so-called container. Together with all its contents, it detaches itself from the hosting OS, is autonomous and can erroneously work on any platform. 

Something similar happens when you move flats. You put your things in boxes, with dishes in one box, clothes — in another, books — in the third one, and so on. So all these things are isolated from one another. When you’re moving house, boxes could be easily transported from one place to another, with no need to unpack and repack each item separately. The same goes with containers inside the containerization technology, which allow for comfortable deployment and transfer of software from one environment to the other, no recompilation or adjustment required.

Why did the containerization idea come to be?

The main reason for containerization technology development — the rise of complex and heavily trafficked IT infrastructure. One should ensure the reliability of each separate component and minimize their mutual impact for their wholesome work. The required operating system and software which can put these elements into containers, divide the large and monolithic IT infrastructures into the numerous smaller ones cooperating as a single unit.

Idea for processes isolation exists for many years. In 2013, Docker showcased Docker Engine and, at the same time, set a standard for using containers with easy-to-use tools, as well as the universal approach to packaging, which accelerated the implementation of container technology. In the summer of 2014, they launched a tool for container management automation (orchestration) — Kubernetes.

How containerization works

The containerization architecture has several layers:

  • Infrastructure. It is a level of hardware. It belongs to a physical computer or a server without an operating system to run the app installed.
  • OS. One of the most popular operating systems is Linux. It works in a local infrastructure, as well as the cloud.
  • Container images. Software developers create and deploy the containers images, that is, files including necessary information to launch a container app. It all happens on the basis of Open Container Initiative (OCI). The containers’ images can be read and can’t be changed by a computer system.
  • Container engine. It is a software that creates containers based on their images. It works as an intermediary between the containers and operating system, providing resources, necessary to the app, and managing them. For example, container engines can control several containers within a single operating system, keeping its autonomy from the basic infrastructure and for one another.
  • App and dependencies. The utmost level of the containerization architecture. It is a code of an app and other files to be run: libraries dependencies and configuration files connected to them. This layer can also have a guest operating system installed on top of the main one.

Containerization advantages

  • Transferability. Containers can work within numerous computing environments: local equipment, virtual machines or cloud platforms.
  • Isolation. In containers, apps work independently, which increases safety and stability, avoids conflicts and provides a sandbox environment.
  • Security. Apps isolation prevents harmful viruses from entering other containers or host systems. Moreover, security permissions can be set to automatically block unauthorized access to containers or restrict communication with unnecessary resources.
  • Efficient resource utilization. Containers are lightweight and use the host system’s core, allowing for efficient use of resources. Multiple containers can run simultaneously on one host, effectively distributing resources and optimizing hardware use.
  • Scalability. Containerization facilitates horizontal scaling, enabling the deployment and scaling of containers across multiple hosts or clusters. They can also be easily replicated and managed with tools like Kubernetes, allowing applications to scale on demand, ensuring high availability and responsiveness.
  • Flexibility and fast deployment. Containers enable rapid application deployment, simplifying the packaging of applications, dependencies, and configurations into a single unit.
  • Version control and collaboration. Developers can work on different components of an application independently in their containers, ensuring compatibility and reducing conflicts. This version control and collaboration boost productivity and simplify the adoption of DevOps practices.

Docker

Docker or Docker Engine is a popular environment for containerization with open source code which helps developers to create, deploy and test container apps on various platforms.

Linux Containers or LXC

Linux containers allow running multiple Linux-based applications on a single host machine. Developers use them to deploy applications that write or read large volumes of data. They don’t replicate the entire operating system in a virtualized environment but consist of necessary functions allocated within the Linux namespace.

Kubernetes

Kubernetes is a popular open-source platform from Google used for deploying, scaling, and managing large numbers of microservices. It features a declarative model that simplifies container automation.

VMware Tanzu

This is a portfolio of VMware products focused on managing modern cloud environments based on containers. With VMware Tanzu, users can develop, maintain, and run containerized applications in Kubernetes clusters in private and public clouds on VMware.

Conclusion

Today, organizations are increasingly using containerization to build new applications and modernize existing ones.

According to an IBM survey, 61% of companies reported that in recent years they have built half of their applications using containerization. This technology allows applications to be “written once and run anywhere”. It speeds up development, avoids vendor lock-in with a single cloud provider, and offers isolation, ease of management, security, and much more.