下载bin包
python-iniparse-0.4-9.el7.noarch.rpm
yum-3.4.3-168.el7.centos.noarch.rpm
yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch.rpm
换yum源
cd /etc/yum.repos.d/
rm -f /etc/yum.repos.d/*
wget -P . http://mirrors.aliyun.com/repo/Centos-7.repo

yum clean all
yum makecache