如果你閱讀文章時，覺得「還不錯？」，請給予LGTM。

前提

我正在参考官方网站。
CentOS Linux 7.8.2003版本（核心）。
确保centos-extras仓库已经启用。
可在以下进行确认。

$ less /etc/yum.repos.d/CentOS-Extras.repo

・执行以下操作以卸载旧的Docker

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

设置Docker仓库

$ sudo yum install -y yum-utils

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

通过这个步骤，将会添加/etc/yum.repos.d/docker-ce.repo文件。

安装Docker Engine

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

执行此命令将安装最新版本的Docker。
如果想要安装特定版本，请执行以下命令并找到对应版本进行安装。

$ yum list docker-ce --showduplicates | sort -r
$ sudo yum install docker-ce-<VERSION_STRING> docker-ce-cli-<VERSION_STRING> containerd.io

启动Docker

$ sudo systemctl start docker

通过这个命令，Docker将被启动。
我们要确认它是否成功启动。

$ sudo systemctl status docker

请确认是否已正常安装

执行hello-world镜像，进行确认。

$ sudo docker run hello-world

如果输出如下，则完成

$ sudo docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
0e03bdcc26d7: Pull complete
Digest: sha256:4cf9c47f86df71d48364001ede3a4fcd85ae80ce02ebad74156906caff5378bc
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/