No package epel-release available
解决方法
wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm
检查是否安装成功：
yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* epel: mirrors.huaweicloud.com
repo id repo name status
base CentOS-7 - Base 9,007
dockerrepo/7 Docker Repository 110
epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64 12,981
repolist: 22,098
