概要

使っていたCentOS にて
急に Yumが使えなくなった

bash

$ sudo yum update
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=vag 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=<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

調査

原因を普通に調べると

インターネットにつながっていない
/etc/resolv.conf が壊れている

が出るが、
どちらもそれ自体はよさそうだった

参考
https://serverfault.com/questions/904304/could-not-resolve-host-mirrorlist-centos-org-centos-7

原因

どうやら、

Centos 7 は本日 2024 年 7 月 1 日に EOL に達したため、mirrorlist.centos.org は不要になりました。パッケージをインストールするには、リポジトリを「mirrorlist」から「baseurl」に調整する必要があります。ほとんどの場合、vault.centos.org は正常に機能します。

とのこと..

解決法

この問題を解決するには、すべての .repo ファイルを一括更新します。

$ sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo
$ sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo
$ sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo

->

bash

$ sudo yum update
..
Success.. OK

参考