报错如下：
Error: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Please verify its path and try again
解决方法：
修改epel.repo文件，修改mirrorlist=https://*****这行，将https修改为http即可正常使用
资料链接：
https://access.redhat.com/discussions/782763
https://www.redhat.com/archives/rhl-list/2009-July/msg02121.html
https://www.redhat.com/archives/epel-devel-list/2012-October/msg00030.html