安装docker步骤

一、卸载旧版本

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

二、使用yum安装docker

# 执行以下命令安装依赖包
sudo yum install -y yum-utils

# 鉴于国内网络问题，强烈建议使用国内源，官方源请在注释中查看。
# 官方源
# $ sudo yum-config-manager \
#     --add-repo \
#     https://download.docker.com/linux/centos/docker-ce.repo

# 执行下面的命令添加 yum 软件源：
sudo yum-config-manager \
    --add-repo \
    https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
sudo sed -i 's/download.docker.com/mirrors.aliyun.com\/docker-ce/g' /etc/yum.repos.d/docker-ce.repo

# 更新 yum 软件源缓存，并安装 docker-ce。
sudo yum install docker-ce docker-ce-cli containerd.io

三、启动docker

sudo systemctl enable docker
sudo systemctl start docker

四、测试docker是否安装正确

docker run --rm hello-world

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:308866a43596e83578c7dfa15e27a73011bdd402185a84c5cd7f32a88b501a24
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/
 
 若能正常输出以上信息，则说明安装成功。

参考文章：

1. https://yeasy.gitbook.io/docker_practice/install/centos
2. https://docs.docker.com/engine/install/centos/
3. https://blog.youkuaiyun.com/baidu_22254181/article/details/82701654