yum提示“Cannot retrieve metalink for repository: epel/x86_64”的解决方法

今天在centos7服务器上用yum的时候发现，yum命令不能用了，不管用yum什么命令都会出现如下提示：


完整的错误提示如下

One of the configured repositories failed (Unknown),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Disable the repository, so yum won't use it by default. Yum will then
        just ignore the repository until you permanently enable it again or use
        --enablerepo for temporary usage:

            yum-config-manager --disable <repoid>

     4. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again

One of the configured repositories failed (Unknown),and yum doesn't have enough cached data to continue.
##其中一个已配置的存储库失败（未知），并且yum没有足够的缓存数据可以继续。
Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again
##无法检索存储库的metalink：epel / x86_64。 请验证其路径，然后重试

1. 定位
   首先我的服务器是ping的通的，，其次 cat /etc/resolv.conf 发现dns也没出现问题
   那么根据错误提示有可能是我的拓展源路径不对
2. 查看拓展源

##查看拓展源
[root@salted ~]# cat /etc/yum.repos.d/epel.repo 
[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
#baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

这里应该改为

[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
#metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch

再执行以下命令

yum clean all
yum makecache
yum update -y

就能解决啦！！