yum install openssl失败了，加 --releasever=8参数也失败了
打开/etc/
打开看下
先备份下
mv ./CentOS-Linux-BaseOS.repo ./CentOS-Linux-BaseOS.repo.bak
然后执行
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.cloud.tencent.com/repo/centos8_base.repo
清空一下yum缓存
yum clean all
然后重建yum缓存
yum makecache
可以看到，又失败了
我们在替换yum源的时候，按照镜像网站的操作方式，只替换了CentOS-Base.repo。
可是在CentOS8中，CentOS-Linux-AppStream.repo的内容没有更新
最好先备份下，我这边直接修改了
vi ./CentOS-Linux-AppStream.repo
# CentOS-Linux-AppStream.repo # # The mirrorlist system uses the connecting IP address of the client and the # update status of each mirror to pick current mirrors that are 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, you can try the commented out # baseurl line instead. #[appstream] #name=CentOS Linux $releasever - AppStream #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=AppStream&infra=$infra #baseurl=http://mirror.centos.org/$contentdir/$releasever/AppStream/$basearch/os/ #gpgcheck=1 #enabled=1 #gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial [appstream] name=Qcloud centos AppStream - $basearch baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/AppStream/$basearch/os/ enabled=1 gpgcheck=1 gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-Official ~ ~
将原来的[appstream]注释掉，然后修改，wq保存
然后再执行重建yum缓存
yum makecache
可以看到，源数据缓存已经建立
接下来继续执行yum install即可
可以看到，已经执行成功了
也可以将CentOS-Linux-AppStream.repo删除，不推荐，注意有的版本叫CentOS-Base.repo和CentOS-AppStream.repo
还有[appstream]有的版本是大写[AppStream]
另附两个源地址
阿里yum源： https://developer.aliyun.com/mirror/centos 腾迅yum源： https://mirrors.tencent.com/help/centos.html
至此问题解决
如果还不行可以查看下网卡配置里的DNS可以先配置为8.8.8.8试一下，或者修改/etc/resolv.conf里的nameserver为8.8.8.8
再不行就是网络受限了，加代理或者解决网络问题