Docker is a platform for developers and system administrators to develop, migrate and run applications. After the application is packaged into a Docker image through Docker, it can be downloaded, started, expanded, deleted and migrated uniformly, which facilitates the deployment and operation of the application. Munity/docs/DOC-42054 Docker adopts server/client mode. Docker clients create, run or deploy Docker containers by interacting with the Docker daemon. Users can install Docker client and Docker daemon on the same system or different systems. Docker clients communicate with Docker daemons through ports or RESTful API. Docker consists of three parts: Docker images:Docker image is a read-only template for creating Docker containers. Images can include Linux operating system, Apache or Web applications. Users can download Docker images that have been created or create Docker images for other users. Each image consists of many layers, and Docker binds these layers in one image through the Union file system. Each image is based on a master image, and then a new layer is added to these master images by operating instructions such as running commands, adding files or directories, or creating an available operating environment. These instructions are saved in the Dockerfile file. Docker registry: Docker registry is used to save Docker images, and it is also divided into public and private. The public Docker registry is Docker Hub, and users can also create private Docker registry to download Docker images for other users. Docker container: It is similar to the directory that stores the configuration files of VMware virtual machines, and can provide all the elements of application running. Docker containers can be run, started, stopped or deleted, and each container is an isolated security application platform.