Introduction to Docker Architecture

Docker Images

A Docker image is a template used to create a Docker container, such as an Ubuntu system.

Docker Container

A container is an independently running application or a group of applications, and is an entity at the runtime of an image.

Docker Client

The Docker client communicates with the Docker daemon through the command line or other tools using the Docker SDK (https://docs.docker.com/develop/sdk/).

Docker Host

A physical or virtual machine used to execute the Docker daemon and containers.

Docker Registry

The Docker repository is used to store images and can be understood as a code repository in code control.

Docker Hub (https://hub.docker.com) provides a huge collection of images for use.

A Docker Registry can contain multiple repositories; each repository can contain multiple tags; each tag corresponds to an image.

Typically, a repository contains images of different versions of the same software, and tags are often used to correspond to different versions of the software. We can use the format of <warehouse name>:<label> to specify which version of the software is the mirror. If no tag is given, latest is used as the default tag.

Docker Machine

Docker Machine is a command line tool that simplifies Docker installation. Through a simple command line, you can install Docker on the corresponding platform, such as VirtualBox, Digital Ocean, and Microsoft Azure.