How to archive a local copy of CentOS 7

• How to archive a local copy of CentOS 7
• What happened?
• What is needed to be done?
  • Hardware and software requirements
  • Internet requirements
  • Sample Rsync script
  • Sample HTTPD config
  • Sample Yum repo config

How to archive a local copy of CentOS 7

This post is meant for the various junior system administrators who have been tasked with fixing problems with CentOS 7 systems after the software was removed from most of its mirrors. Most of these systems have probably been running fine for a decade, and now possible critical systems are generating failed cron jobs or other errors.

What happened?

On July 1st, 2024, CentOS Enterprise Linux 7 reached its end of life as its upstream, Red Hat Enterprise Linux 7, had moved to Extended Life(cycle) Support. As with previous releases, the operating system was moved from the main mirrors to the CentOS vault, and the mirrorlists were turned off. Once the software was removed from the main mirrors, many secondary mirrors also removed the software as rsync and similar scripts would see the old software was gone. At this point, some unknown number of CentOS Linux systems ended up ‘non-supported.’

The systems may have been extremely low maintenance for years running whatever tasks they had been without a problem. The people who initially set them up have probably moved to other jobs, and some new person is now finding out that things are broken. Maybe its a cron job which runs one a week to run updates, or the kickstart used to reinstall an old server now breaks. In most of these cases, there is little documentation on what is being used, why it is being used, or how big a problem this is going to be.

What is needed to be done?

Getting an infrastructure out of this place is really out of scope of a single blog post. It generally requires getting various levels of managements attention, and then long term planning on how to transform an infrastructure into something more manageable. However in the short term a site can make things workable by making a local mirror of content from an upstream vault.

The reason to use a local vault is that the existing upstream vaults are limited in bandwidth and scope. Plus as more sites try to use them, the services may be curtailed or removed. When dealing with ‘End of Life’ projects and software, it is better to assume that things will get worse before they get better.

Hardware and software requirements

In order to mirror CentOS 7 locally, you are going to need to set up a webserver with at least 500 GB of free space (if you don’t want to copy the out of date ‘atomic’ trees. ) The amount of memory and cpu cores needed is dependent on the number of servers you are going to be supporting. The more systems, the more memory and cores that might be needed. In any case, I was able to set up a system with 2 cores and 4 GB of ram to support 4 EL7 systems without problems.

Internet requirements

There are currently 3 major mirrors of the CentOS vault.

• archive.kernel.org
• linuxsoft.cern.ch
• mirror.nsc.liu

It is best to find one which is ‘network’ close and set up scripts to rsync data from the site. I found that each server will be busier at different times, so expect that copying will take multiple hours.

Sample Rsync script

The script I used to do this was the following:

#!/bin/bash

VAULT=archive.kernel.org::centos-vault/
TREEDIR=/srv/mirrors/

RSYNC_OPTS='-avSHP --delete-excluded'

## Mirror CentOS 7
mkdir -vp ${TREEDIR}/centos-vault/7.9/
EXCLUDE_ITEMS="--exclude=atomic/"
rsync ${RSYNC_OPTS} ${EXCLUDE_ITEMS}  ${VAULT}/7.9.2009/ ${TREEDIR}/centos-vault/7.9/

Sample HTTPD config

In my /etc/httpd/conf.d/ I added the following config file:

Alias "/mirrors" "/srv/mirrors"
<Directory /srv/mirrors>
  AllowOverride None
  Require all granted
  Options +Indexes
</Directory>

Sample Yum repo config

Finally on the EL7 systems, I used a config like the following in /etc/yum.repos.d/CentOS-EOL.repo

[base]
name=CentOS-$releasever - Base
baseurl=http://192.168.1.150/mirrors/centos-vault/7.9/os/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=http://192.168.1.150/mirrors/centos-vault/7.9/updates/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=http://192.168.1.150/mirrors/centos-vault/7.9/extras/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

[centosplus]
name=CentOS-$releasever - Plus
baseurl=http://192.168.1.150/mirrors/centos-vault/7.9/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

At this point, updates were possible and I was able to reinstall a system in order to rebuild some packages I needed. Similar work can be done to set up mirrors of CentOS Linux 6 or third party repositories like EPEL.