执行命令：
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
报错；
已加载插件：fastestmirror
adding repo from: https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
grabbing file https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo
Could not fetch/save url https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo to file /etc/yum.repos.d/docker-ce.repo: [Errno 14] curl#60 - "Peer's Certificate has expired."
解决：
做时间同步即可
安装ntpdate
yum -y install ntpdate
进行同步
ntpdate ntp1.aliyun.com
