Centos 更新yum源出现 AppStream‘ 缓存失败，忽略这个 repo。同步仓库 ‘base‘ 缓存失败，忽略这个 repo 的问题，踩坑记录

今天在安装docker 镜像和容器，发现国外的yum源没办法更新，然后尝试更换aliyun 源，结果出现了几个大坑，在此记录，希望后续的兄弟们别掉坑里。

首先修改 CentOS-Base.repo ， root 下执行 vim CentOS-Base.repo

需改内容如下：

# 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
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/BaseOS/$basearch/os/
gpgcheck=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

#additional packages that may be useful
[extras]
name=CentOS-8.5.2111 - Extras - mirrors.aliyun.com
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/extras/$basearch/os/
gpgcheck=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-8.5.2111 - Plus - mirrors.aliyun.com
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/centosplus/$basearch/os/
gpgcheck=0
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

[PowerTools]
name=CentOS-8.5.2111 - PowerTools - mirrors.aliyun.com
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/PowerTools/$basearch/os/
gpgcheck=0
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official


[AppStream]
name=CentOS-8.5.2111 - AppStream - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
gpgcheck=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-Official

这里需要注意，网络流传版本的结果方法其他地方都没有问题，但是就这个节点：[AppStream]
路径要注意，不能用 releasever 来通配版本号,事实上我发现阿里云的源这里已经换成了 8-stream
正确的应该是 baseurl=http://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
然后继续修改 CentOS-AppStream.repo root 下执行命令 vim CentOS-AppStream.repo

#CentOS-AppStream.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.
#
#

[AppStream]
name=CentOS-$releasever - AppStream
baseurl=http://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

这里也一样，
正确的应该是 baseurl=http://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
然后 yum clean all yum makecache 重建元数据缓存，此时就可以看到docker 的更新源文件了。