备份源

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
mv /etc/yum.repos.d/CentOS-SCLo-scl.repo /etc/yum.repos.d/CentOS-SCLo-scl.repo.bak
mv /etc/yum.repos.d/CentOS-SCLo-scl-rh.repo /etc/yum.repos.d/CentOS-SCLo-scl-rh.repo.bak

下载阿里的源

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

编辑 CentOS-SCLo-scl.repo

[centos-sclo-sclo]
name=CentOS-7 - SCLo sclo
baseurl=https://mirrors.aliyun.com/centos/7/sclo/x86_64/sclo/
# mirrorlist=http://mirrorlist.centos.org?arch=$basearch&release=7&repo=sclo-sclo
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-SCLo

编辑 CentOS-SCLo-scl-rh.repo

[centos-sclo-rh]
name=CentOS-7 - SCLo rh
baseurl=https://mirrors.aliyun.com/centos/7/sclo/x86_64/rh/
# mirrorlist=http://mirrorlist.centos.org?arch=$basearch&release=7&repo=sclo-rh
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-SCLo

处理缓存

yum clean all
yum makecache

参考：

https://www.qyidc.net/knowledgebaseview?id=46