1.如果系统安装过docker，先卸载docker

sudo yum remove docker  docker-common docker-selinux dockesr-engine

2.更新yum软件信息

sudo yum update

3.设置yum的docker-ce源

# 下载docker-ce源
wget -O /etc/yum.repos.d/docker-ce.repo https://download.docker.com/linux/centos/docker-ce.repo

# 替换源地址为清华镜像站
sudo sed -i 's+download.docker.com+mirrors.tuna.tsinghua.edu.cn/docker-ce+' /etc/yum.repos.d/docker-ce.repo

如果网络太渣，下载不下来，也可以在/etc/yum.repos.d/下新增docker-ce.repo文件，内容如下：

[docker-ce-stable]
name=Docker CE Stable - $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/$basearch/stable
enabled=1
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-stable-debuginfo]
name=Docker CE Stable - Debuginfo $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/debug-$basearch/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-stable-source]
name=Docker CE Stable - Sources
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/source/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-test]
name=Docker CE Test - $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-test-debuginfo]
name=Docker CE Test - Debuginfo $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/debug-$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-test-source]
name=Docker CE Test - Sources
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/source/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-nightly]
name=Docker CE Nightly - $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-nightly-debuginfo]
name=Docker CE Nightly - Debuginfo $basearch
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/debug-$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

[docker-ce-nightly-source]
name=Docker CE Nightly - Sources
baseurl=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/$releasever/source/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/gpg

4.安装docker

sudo yum install -y docker-ce

5.启动docker，并加入开机启动列表

sudo systemctl start docker
sudo systemctl enable docker