2024年6月30日后，CentOS 7 将不再提供更新和支持，正式停止维护，但我的项目几乎都是基于Centos7来部署的，在执行yum指令的时候会报错

错误如下：

[root@localhost ~]# yum update
已加载插件：fastestmirror, langpacks
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; 未知的错误"


 One of the configured repositories failed (未知),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=<repoid> ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable <repoid>
        or
            subscription-manager repos --disable=<repoid>

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64

解决方法，执行：

sed -i -r -e 's|^mirrorlist=|#mirrorlist=|g' -e 's|^#?baseurl=http://mirror.centos.org/centos|baseurl=https://vault.centos.org/centos|g' -e 's|^#?baseurl=http://mirror.centos.org/altarch|baseurl=https://vault.centos.org/altarch|g' -e 's|^#?baseurl=http://download.fedoraproject.org|baseurl=http://download.fedoraproject.org|g' /etc/yum.repos.d/CentOS-*.repo

然后重新构建缓存：

yum clean all && yum makecache