Why docker is not a container

From the moment containerization technology was born, Docker has become a leader in this field. However, one voice is getting louder and louder, and it has to do with Docker not being a "container." This sentence is incredible, because Docker has always been synonymous with containerization technology, and people are talking about Docker Container.

So, why do some people say that Docker is not a "container"? How to understand this problem? This article will analyze why Docker is not a "container" from the perspective of technical implementation principles and philosophy.

1. Technical Implementation Principle

Docker’s original idea was not containerization, but to encapsulate it based on LXC (Linux Container) and present it with a set of REST APIs Come out and make it easier for application developers to use it. This is the original idea of ​​Docker. Docker technology initially supports single-process programs, which is based on submitting an Image image file. Once the image is submitted, Docker can start one or more containers through the image, and the application process is running in the container.

Compared with traditional virtualization technologies (such as VMWare, Virtual Box), Docker uses process-level isolation, that is, multiple containers on the same host can share the same set of operating system kernels. This can save a lot of resource overhead and easily achieve features such as rapid deployment, quick startup, quick migration, and version management.

In fact, Docker technology has improved and improved the original LXC technology and encapsulated it into a more lightweight and powerful container engine. From this perspective, Docker is not a native container technology, but an encapsulation and enhancement of containers, so some people say that Docker is not a "container".

2. Philosophical level

In addition, there is another issue to consider from the philosophical level of Docker. Docker does not really install, configure, run and install "containers". Remove these aspects of management. In Docker, image building, updating, and version control are still managed by developers themselves. This means that Docker has not fully developed a unified mechanism to manage containers and images, which requires more or less manual work.

Moreover, Docker encapsulates the underlying container technology too much, making it too complex and easily confusing for beginners. And it contains too many pitfalls and limitations, which complicates containerization, a method that originally simplifies the process.

From this perspective, especially from the engineering implementation level, Docker cannot be classified as a "container" because it still needs to be improved mechanically.

3. Is Docker a container?

Since the answer to the above two points is "no", what are the nature and characteristics of the Docker system? There is no doubt that Docker is a solution for application environment deployment and management, which is closely related to container technology. The benefits of Docker lie in its excellent operational simplicity, efficient sandbox mechanism, convenient image creation and sharing methods, and convenience in deploying containers. What Docker brings to people is a more scientific, faster and more convenient deployment method. Therefore, Docker can be seen as an application environment solution rather than a "container" dry matter.

Summary

This article explains why some people say that Docker is not a "container" from two aspects: Docker technology implementation principle and philosophical level. In fact, Docker is defined as a solution for application environment deployment and management. This does not mean that Docker replaces or does not require container technology, but it shows that Docker technology is based on the enhancement of container technology and better realizes the value of container technology. Although the nature and characteristics of Docker are not containers, the changes brought by Docker are a major leap forward in application environment management, bringing great convenience and flexibility.

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