如何解决yum无法安装epel-release的问题

# 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-$releasever - Base
    #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
    #baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
    #baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
    baseurl=http://vault.centos.org/7.9.2009/os/$basearch/
    gpgcheck=1
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
     
    #released updates 
    [updates]
    name=CentOS-$releasever - Updates
    #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
    #baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
    #baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
    baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/
    gpgcheck=1
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
     
    #additional packages that may be useful
    [extras]
    name=CentOS-$releasever - Extras
    #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
    #$baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
    #baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
    baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/
    gpgcheck=1
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
     
    #additional packages that extend functionality of existing packages
    [centosplus]
    name=CentOS-$releasever - Plus
    #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
    #baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
    #baseurl=http://vault.centos.org/7.9.2009/x86_64/os/
    baseurl=http://vault.centos.org/7.9.2009/centosplus/$basearch/
    gpgcheck=1
    enabled=0
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

sudo yum clean all
sudo yum makecache

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo

cat CentOS-Base.repo`

#建议是备份一下

rm -rf /etc/yum.repos.d mkdir /etc/yum.repos.d

wget http://mirrors.aliyun.com/repo/Centos-7.repo cp Centos-7.repo /etc/yum.repos.d/CentOS-Base.repo

#安装 rpm -ivh wget-1.14-15.el7_4.1.x86_64.rpm

yum clean all yum makecache