What is the use of docker image?

The uses of docker images: 1. The image is the prerequisite for Docker to run the container. The warehouse is the place where the image is stored, and it is the core of Docker; 2. The image can be regarded as a special file system. In addition to providing containers In addition to the programs, libraries, resources, configuration and other files required for runtime, it also contains some configuration parameters prepared for runtime.

Use of docker image:

Previous Docker command map:

It can be seen that Docker contains three basic concepts, namely image (Image), container (Container) and warehouse (Repository ). The image is the prerequisite for Docker to run the container. The warehouse is the place where the image is stored. It can be seen that the image is the core of Docker.

Back to the topic, the Docker image can be regarded as a special file system. In addition to providing the programs, libraries, resources, configuration and other files required for the container to run, it also contains some files prepared for the runtime. Some configuration parameters (such as anonymous volumes, environment variables, users, etc.). The image does not contain any dynamic data, and its content will not be changed after it is built.

If you want to have a deeper understanding of Docker mirroring, the principle of mirroring is also essential, and the most important concept is mirroring layers (Layers) (as shown below). The image layer relies on a series of underlying technologies, such as file systems, copy-on-write, union mounts, etc. Fortunately, you can learn these technologies in many places. I won’t go into the technical details here.

In general, the most important thing to remember is that each instruction in the Dockerfile creates an image layer, which in turn increases the overall image size.

As one of Docker’s most prominent innovations, mirroring has revolutionized software delivery standards. Understanding images is very important to understanding the entire Docker life cycle.

Related tutorial recommendations: docker tutorial

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