Docker(1)-install Docker

The machine I use:

1. CentOS 7 (Tencent's cloud server)

table of Contents

1. What is Docker

2. Installation prerequisites

Three, installation steps

1. Download Docker
   • Install using the source Docker repository
   • Download files to install manually
2. Install Docker
3. Run example

Four, additional operations

1. Docker change source (speed up Docker image download)
2. Old version of Docker uninstall

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1. What is Docker

  Docker is an open source application container engine that allows developers to package their applications and dependencies into a portable image, and then publish it to any popular Linux or Windows machine, which can also be virtualized. Containers use the sandbox mechanism completely, and there will be no interfaces between them.
Docker image is here

Advantages :

1. Docker saves us a lot of production environment testing, because the development environment is your production environment
2. Docker can better utilize (ya) and (zha) computer performance

2. Installation prerequisites

1. If you have installed an old version of Docker, please uninstall it first, please read step 2 of the additional steps
2. You need a computer (or server) with Windows/macOS/Linux
3. Have a stable internet connection
4. Read this article carefully and patiently hhh

Three, installation steps

1. Download Docker
   a. Use Docker's warehouse

   Install dependencies

   sudo yum install -y yum-utils \   
                       device-mapper-persistent-data \ 
                       lvm2
   

   To add a warehouse (stable version) and
   wish to use other versions, please refer to this part of the command in the official Docker documentation !
   

   sudo yum-config-manager \
               --add-repo \
   https://download.docker.com/linux/centos/docker-ce.repo
   

   Should see

   repo saved to /etc/yum.repos.d/docker-ce.repo
   

   b. Download the file and install it manually

   (Dig the hole first, fill it in when you have time)

2. Install Docker

   sudo yum install docker-ce docker-ce-cli containerd.io
   

   Show Compelete! to go to the next step
   Tips: If GPG key verification appears, please check if the key matches the following string

   060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35
   

3. Start Docker

   sudo systemctl start docker  
   ps -ef | grep docker
   

   As long as dockerd appears, it proves that docker started successfully

   root     30820     1  0 14:10 ?        00:00:00 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
   root     31127 23503  0 14:11 pts/0    00:00:00 grep --color=auto docker
   

4. Run the Hello World example

   [root@VM_0_15_centos ~]# docker run hello-world
   Unable to find image 'hello-world:latest' locally
   latest: Pulling from library/hello-world
   1b930d010525: Pull complete 
   Digest: sha256:d1668a9a1f5b42ed3f46b70b9cb7c88fd8bdc8a2d73509bb0041cf436018fbf5
   Status: Downloaded newer image for hello-world:latest
   Hello from Docker!
   This message shows that your installation appears to be working correctly.
     
   To generate this message, Docker took the following steps:
   1. The Docker client contacted the Docker daemon.
   2. The Docker daemon pulled the "hello-world" image from the Docker Hub.(amd64)
   3. The Docker daemon created a new container from that image which runs the executable that produces the output you are currently reading.
   4. The Docker daemon streamed that output to the Docker client, which sent it to your terminal.
     
   To try something more ambitious, you can run an Ubuntu container with:
   $ docker run -it ubuntu bash
     
   Share images, automate workflows, and more with a free Docker ID:
   https://hub.docker.com/
     
   For more examples and ideas, visit:
   https://docs.docker.com/get-started/
   

   Then it proves that Docker has been installed and can be used normally

Four, optional operations

1. Docker change source

   cd /etc/docker
   vim daemon.json
   

   Add the following content to the daemon.json file

   {
   	"registry-mirrors": [
   		"https://registry.docker-cn.com",
   		"http://hub-mirror.c.163.com",
   		"https://docker.mirrors.ustc.edu.cn",
   		"https://registry.docker-cn.com",
   		"https://docker.mirrors.ustc.edu.cn"
   	],
   	"dns": ["223.5.5.5","223.6.6.6"]
   }
   

   Then restart Docker

   systemctl restart docker.service
   

2. Uninstall the old version of Docker

   sudo yum remove docker \
                    docker-client \
                    docker-client-latest \
                    docker-common \
                    docker-latest \
                    docker-latest-logrotate \
                    docker-logrotate \
                    docker-engine
   

   After completing this step, yum will report that all the above packages have not been installed,
   and the images, containers, sub-volumes and network configuration under /var/lib/docker/ will be preserved

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Part of the article is my own view of Docker, which does not mean that it is absolutely correct.