centos直接使用默认的yum源经常会安装失败，所以最好换成国内的源，经过测试，自己的服务器上用清华的镜像成功率是最高的，其官方地址是 https://mirrors.tuna.tsinghua.edu.cn/ ，从中选择具体的每个镜像使用帮助。
建议先备份 CentOS-Base.repo
sudo cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak然后编辑 /etc/yum.repos.d/CentOS-Base.repo 文件，在 mirrorlist= 开头行前面加 # 注释掉；并将 baseurl= 开头行取消注释（如果被注释的话），把该行内的域名（例如mirror.centos.org）替换为 mirrors.tuna.tsinghua.edu.cn。
或者，你也可以直接使用如下内容覆盖掉 /etc/yum.repos.d/CentOS-Base.repo 文件：
# CentOS-Base.repo # # The mirror system uses the connecting IP address of the client and the # update status of each mirror to pick mirrors that are updated to and # geographically close to the client. You should use this for CentOS updates # unless you are manually picking other mirrors. # # If the mirrorlist= does not work for you, as a fall back you can try the # remarked out baseurl= line instead. # # [base] name=CentOS-$releasever - Base baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-7 #released updates [updates] name=CentOS-$releasever - Updates baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-7 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-7 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus gpgcheck=1 enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-7最后，更新软件包缓存
sudo yum makecache安装docker的过程真的是花费了好多时间，最后的docker-ce一直超时，重复了好几遍才安装成功
如果你之前安装过 docker，请先删掉
sudo yum remove docker docker-common docker-selinux docker-engine安装一些依赖
sudo yum install -y yum-utils device-mapper-persistent-data lvm2下载repo文件
wget -O /etc/yum.repos.d/docker-ce.repo https://download.docker.com/linux/centos/docker-ce.repo把软件仓库地址替换为 TUNA:
sudo sed -i 's+download.docker.com+mirrors.tuna.tsinghua.edu.cn/docker-ce+' /etc/yum.repos.d/docker-ce.repo最后安装:
sudo yum makecache fast sudo yum install docker-ce最后一步可能会下载一部分就失败了，多试几次，总会成功的…
启动docker
sudo systemctl start docker