参考：
https://jingyan.baidu.com/article/f0062228fff083bad2f0c873.html
https://www.cnblogs.com/heqiuyu/p/14268937.html

上面从 http://mirrors.aliyun.com/repo/Centos-8.repo 下载的文件并不能直接使用，需要根据需要做如下修改：

• 查看当前centos版本

 cat /etc/redhat-release 
 CentOS Linux release 8.5.2111

当前的版本时8.5.2111，然后看https://mirrors.aliyun.com/centos-vault/ 有没有对应的版本：

然后修改Centos-8.repo：

# 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-8.5.2111 - Base - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/8.5.2111/BaseOS/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
#additional packages that may be useful
[extras]
name=CentOS-8.5.2111 - Extras - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/8.5.2111/extras/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-8.5.2111 - Plus - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/8.5.2111/centosplus/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
[PowerTools]
name=CentOS-8.5.2111 - PowerTools - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/8.5.2111/PowerTools/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official


[AppStream]
name=CentOS-8.5.2111 - AppStream - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/8.5.2111/AppStream/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official

[debuginfo]
name=CentOS Linux $releasever - Debuginfo
baseurl=http://mirrors.aliyun.com/centos-debuginfo/$releasever/$basearch/
gpgcheck=1
enabled=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official

或者改成如下：
CentOS-Base.repo:

# 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-centos/$releasever - Base - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/centos/$releasever/BaseOS/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
#additional packages that may be useful
[extras]
name=CentOS-centos/$releasever - Extras - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/centos/$releasever/extras/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-centos/$releasever - Plus - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/centos/$releasever/centosplus/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official
 
[PowerTools]
name=CentOS-centos/$releasever - PowerTools - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/centos/$releasever/PowerTools/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official


[AppStream]
name=CentOS-centos/$releasever - AppStream - mirrors.aliyun.com
#failovermethod=priority
baseurl=https://mirrors.aliyun.com/centos-vault/centos/$releasever/AppStream/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official

[debuginfo]
name=CentOS Linux $releasever - Debuginfo
baseurl=http://mirrors.aliyun.com/centos-debuginfo/$releasever/$basearch/
gpgcheck=1
enabled=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-Official