Docker Image Build Process Explained

The build process of Docker images can be summarized in the following steps:

1. Preparing base image: Docker images are built from layers of file systems, where each layer is read-only. When creating a new Docker image, it typically starts with an existing base image, such as an operating system image or an application image.
2. Executing instructions in a Dockerfile: Building a Docker image typically involves writing a Dockerfile containing Docker build instructions, such as copying files, running commands, setting environment variables, etc. During the build process, the Docker engine will execute the instructions in the Dockerfile one by one, creating a new image layer on top of the current base image each time an instruction is executed.
3. Create a new image: After all the instructions have been executed, the Docker engine will combine these image layers together to generate a new image. This new image contains all the configurations and files defined in the Dockerfile, and can be used to create Docker containers for running.

Overall, the construction principle of Docker images is to create an image containing specific configurations and files through multiple layered file systems and commands in the Dockerfile. This image-building method allows Docker to easily package, distribute, and deploy applications.