Live migration of a RedHat Enteprise Linux 8.0 to Centos 8.0

RHEL 8 to CentOS 8 migration guide.

If you tried a RHEL 8 Beta or you have a Developer’s License of RedHat Enterprise Linux 8 and you want / need to migrate to CentOS 8 for any reason (licensing, cost, hobby, fun) without loosing any data you can do it like this:

Importing CentOS 8 Keys

First of all you need to download, rename and import the CentOS 8 key or yum will fail like this:

 
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warning: /var/cache/dnf/AppStream-31fadb45047f5928/packages/GConf2-3.2.6-22.el8.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID 8483c65d: NOKEY
CentOS-8 - AppStream                                                                                                                  0.0  B/s |   0  B     00:00
Curl error (37): Couldn't read a file:// file for file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial [Couldn't open file /etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial]

Run this commands:

 
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[root@server1 ~]# cd /etc/pki/rpm-gpg/
[root@server1 ~]# wget https://www.centos.org/keys/RPM-GPG-KEY-CentOS-Official
[root@server1 ~]# cp RPM-GPG-KEY-CentOS-Official RPM-GPG-KEY-centosofficial
[root@server1 ~]# gpg --quiet --with-fingerprint RPM-GPG-KEY-centosofficial

Change Repositories from Redhat’s to CentOS

Disable the subscription manager repo of Redhat:

 
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[root@server1 ~]# subscription-manager config --rhsm.manage_repos=0

Move redhat.repo somewhere else:

 
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[root@server1 ~]# cd /etc/yum.repos.d/
[root@server1 ~]# mv redhat.repo /root/

Create or Download CentOS repos:

You need:

CentOS-AppStream.repo CentOS-Base.repo CentOS-Extras.repo CentOS-PowerTools.repo inside /etc/yum.repos.d/

You can create them copying them from here:

 
 
 
 
 
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[root@server1 yum.repos.d]# cat CentOS-AppStream.repo
 
[AppStream]
name=CentOS-$releasever - AppStream
mirrorlist=http://mirrorlist.centos.org/?release=$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

 
 
 
 
 
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[root@server1 yum.repos.d]# cat CentOS-Base.repo
 
[BaseOS]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=BaseOS&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/BaseOS/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

 
 
 
 
 
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[root@server1 yum.repos.d]# cat CentOS-Extras.repo
 
[extras]
name=CentOS-$releasever - Extras
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/extras/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

 
 
 
 
 
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[root@server1 yum.repos.d]# cat CentOS-PowerTools.repo
 
 
[PowerTools]
name=CentOS-$releasever - PowerTools
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=PowerTools&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/PowerTools/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

Now you have no redhat repos and only CentOS 8 repos in your system. Clean yum:

 
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[root@server1 ~]# yum clean all

And try an update:

 
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[root@server1 ~]# yum update

It should reinstall every package from the CentOS 8 Repositories.

If it does not, try to create a rpmlist of all installed packages and xargs it to reinstall manually:

 
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[root@server1 ~]# rpm -qa | sort | sed 's/-[0-9].*[0-9]*//g' > filelist.txt

 
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[root@server1 ~]# cat filelist.txt | xargs yum reinstall -y

If you succeed you should see yum loading only CentOS Repos when issuing a yum install / reinstall like this:

 
 
 
 
 
 
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[root@server1 ~]# yum reinstall yum
Updating Subscription Management repositories.
CentOS-8 - AppStream 1.4 MB/s | 6.0 MB 00:04
CentOS-8 - Base 1.2 MB/s | 7.9 MB 00:06
CentOS-8 - Extras 671 B/s | 2.1 kB 00:03
CentOS-8 - PowerTools 485 kB/s | 1.8 MB 00:03
Extra Packages for Enterprise Linux 8 - x86_64 513 kB/s | 2.2 MB 00:04
Dependencies resolved.
======================================================================================================================================================================
Package Arch Version Repository Size
======================================================================================================================================================================
Reinstalling:
yum noarch 4.0.9.2-5.el8 BaseOS 173 k
 
Transaction Summary
======================================================================================================================================================================
 
Total download size: 173 k
Installed size: 59 k
Is this ok [y/N]:

You can also uninstall subscription manager now:

 
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yum erase dnf-plugin-subscription-manager

 
 
 
 
 
 
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[root@freedom ~]# yum erase dnf-plugin-subscription-manager
Updating Subscription Management repositories.
Dependencies resolved.
======================================================================================================================================================================
Package Arch Version Repository Size
======================================================================================================================================================================
Removing:
dnf-plugin-subscription-manager x86_64 1.23.8-35.el8 @BaseOS 82 k
Removing dependent packages:
subscription-manager-cockpit noarch 1.23.8-35.el8 @BaseOS 3.2 M
subscription-manager-plugin-container x86_64 1.23.8-35.el8 @BaseOS 15 k
Removing unused dependencies:
python3-ethtool x86_64 0.14-3.el8 @BaseOS 92 k
python3-inotify noarch 0.9.6-13.el8 @BaseOS 243 k
python3-subscription-manager-rhsm x86_64 1.23.8-35.el8 @BaseOS 369 k
subscription-manager x86_64 1.23.8-35.el8 @BaseOS 4.2 M
subscription-manager-rhsm-certificates x86_64 1.23.8-35.el8 @BaseOS 0
 
Transaction Summary
======================================================================================================================================================================
Remove 8 Packages
 
Freed space: 8.2 M
Is this ok [y/N]: y
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Running scriptlet: subscription-manager-plugin-container-1.23.8-35.el8.x86_64 1/1
Erasing : subscription-manager-plugin-container-1.23.8-35.el8.x86_64 1/8
Erasing : subscription-manager-cockpit-1.23.8-35.el8.noarch 2/8
Running scriptlet: subscription-manager-1.23.8-35.el8.x86_64 3/8
Erasing : subscription-manager-1.23.8-35.el8.x86_64 3/8
warning: /etc/rhsm/rhsm.conf saved as /etc/rhsm/rhsm.conf.rpmsave
 
Running scriptlet: subscription-manager-1.23.8-35.el8.x86_64 3/8
Erasing : python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64 4/8
Erasing : subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64 5/8
Erasing : python3-inotify-0.9.6-13.el8.noarch 6/8
Erasing : dnf-plugin-subscription-manager-1.23.8-35.el8.x86_64 7/8
Erasing : python3-ethtool-0.14-3.el8.x86_64 8/8
Running scriptlet: python3-ethtool-0.14-3.el8.x86_64 8/8
Verifying : dnf-plugin-subscription-manager-1.23.8-35.el8.x86_64 1/8
Verifying : python3-ethtool-0.14-3.el8.x86_64 2/8
Verifying : python3-inotify-0.9.6-13.el8.noarch 3/8
Verifying : python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64 4/8
Verifying : subscription-manager-1.23.8-35.el8.x86_64 5/8
Verifying : subscription-manager-cockpit-1.23.8-35.el8.noarch 6/8
Verifying : subscription-manager-plugin-container-1.23.8-35.el8.x86_64 7/8
Verifying : subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64 8/8
 
Removed:
dnf-plugin-subscription-manager-1.23.8-35.el8.x86_64 subscription-manager-cockpit-1.23.8-35.el8.noarch
subscription-manager-plugin-container-1.23.8-35.el8.x86_64 python3-ethtool-0.14-3.el8.x86_64
python3-inotify-0.9.6-13.el8.noarch python3-subscription-manager-rhsm-1.23.8-35.el8.x86_64
subscription-manager-1.23.8-35.el8.x86_64 subscription-manager-rhsm-certificates-1.23.8-35.el8.x86_64
 
Complete!
[root@freedom ~]# yum update
Last metadata expiration check: 0:02:33 ago on Tue 15 Oct 2019 07:01:01 PM EEST.
Dependencies resolved.
Nothing to do.
Complete!
[root@freedom ~]#

Don’t forger to grub2-mkconfig !

On RHEL the path is:

grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

You need to use /centos/ like this:

 
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grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg

How to Migrate from RHEL 8 to CentOS 8

Live migration of a RedHat Enteprise Linux 8.0 to Centos 8.0

Importing CentOS 8 Keys

Change Repositories from Redhat’s to CentOS

Create or Download CentOS repos: