Solving a problem with CentOS 7 repositories

In 2024, the support period for the popular CentOS 7 operating system, which many users and server admins considered the de facto standard for use on their physical and virtual servers, ended. The era of CentOS 7 is over, and it has been replaced by newer OSes

But what do you do when the operating system is running like clockwork and there is no sense, opportunity or desire to upgrade a perfectly working and reliable system to newer releases? After the end of support, CentOS 7 users faced the problem that the standard repositories from which they could install utilities or non-essential libraries became unavailable

When we ran the yum update, we saw the following:

#yum update -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
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; Unknown error"


 One of the configured repositories failed (Unknown),
 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= ...

     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 
        or
            subscription-manager repos --disable=

     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=.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64
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Put aside the panic. Fortunately, the problem is quite simple to solve. The official CentOS 7 repositories have moved to a new address, all you need to do is replace some URLs and disable unnecessary repositories

All you need to do is run three commands as root

sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/CentOS-*.repo
sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/CentOS-*.repo
sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/CentOS-*.repo
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Done! Now we can install any packages from the standard CentOS 7 repository