卸载：
sudo yum remove docker                   docker-client                   docker-client-latest                   docker-common                   docker-latest                   docker-latest-logrotate                   docker-logrotate                   docker-engine

yum install -y yum-utils
设置镜像仓库：

sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo　　#默认,建议不用，网速太慢会使安装超程序时退出。

yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo　　　#使用阿里云镜像代理

yum clean all　　#yum 会把下载的软件包和header存储在cache中而不自动删除。如果觉得占用磁盘空间，可以使用yum clean指令清除缓存

yum makecache fast　　#命令是将软件包信息提前在本地缓存一份，用来提高搜索安装软件的速度

yum install docker-ce docker-ce-cli containerd.io　　#下面是三个程序的解释

containerd.io - daemon to interface with the OS API (in this case, LXC - Linux Containers), essentially decouples Docker from the OS, also provides container services for non-Docker container managers
docker-ce - Docker daemon, this is the part that does all the management work, requires the other two on Linux
docker-ce-cli - CLI tools to control the daemon, you can install them on their own if you want to control a remote Docker daemon

#启动和查看docker状态
systemctl start docker
systemctl status docker

docker version

#试用docker
docker run hello-world

docker images

卸载

yum remove docker-ce docker-ce-cli containerd.io

rm -rf /var/lib/docker

rm -rf /var/lib/containerd