下载阿里源，makecache后报错

[root@python01 yum.repos.d]# yum makecache
CentOS-8 - Base - mirrors.aliyun.com 77 B/s | 2.3 kB 00:30
Errors during downloading metadata for repository 'base':
- Status code: 404 for https://mirrors.aliyun.com/centos/8/BaseOS/x86_64/os/repodata/repomd.xml (IP: 106.15.218.236)
- Curl error (28): Timeout was reached for http://mirrors.aliyuncs.com/centos/8/BaseOS/x86_64/os/repodata/repomd.xml [Connection timed out after 30000 milliseconds]
- Status code: 404 for http://mirrors.cloud.aliyuncs.com/centos/8/BaseOS/x86_64/os/repodata/repomd.xml (IP: 100.100.2.148)
Error: Failed to download metadata for repo 'base': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

查了一下centos 8版本的信息，发现官方到2021年12月31日后就不再维护该系统了，而阿里源的正式版本的源也已经关闭，但阿里同时也整了一个centos8-stream版本的源维护：​ ​https://mirrors.aliyun.com/centos/8-stream/​​

解决方法就是，将CentOS-Base.repo原有的内容清除，替换成以下的

[base]
name=CentOS-8-stream - Base - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos/8-stream/BaseOS/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

#additional packages that may be useful
[extras]
name=CentOS-8-stream - Extras - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos/8-stream/extras/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-8-stream - Plus - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos/8-stream/centosplus/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

[PowerTools]
name=CentOS-8-stream - PowerTools - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos/8-stream/PowerTools/$basearch/os/
gpgcheck=1
enabled=0
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

[AppStream]
name=CentOS-8-stream - AppStream - mirrors.aliyun.com
baseurl=https://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official