1、将源文件备份

cd /etc/yum.repos.d/ && mkdir backup && mv *repo backup/

2、下载阿里源文件

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo

3、更新源里面的地址

sed -i -e "s|mirrors.cloud.aliyuncs.com|mirrors.aliyun.com|g " /etc/yum.repos.d/CentOS-*
sed -i -e "s|releasever|releasever-stream|g" /etc/yum.repos.d/CentOS-*

4、生成缓存

yum clean all && yum makecache