Migrate CentOS 8 to AlmaLinux 8
After the release of CentOS 8 we assumed the usual 10-year lilfecycle like it is common in the RHEL world. Bugfixes and feature backports from newer versions in the early years of that period and plain security fixes towards the end of the distribution's lifetime are commonly provided. After RedHat had been acquired by IBM the work on CentOS 8 had been stopped early (2021-12-31) and the focus shifted to CentOS Stream, a kind of preview for the next RHEL point release. As CentOS Stream is somewhat ahead, software versions may differ and lead to compatibility problems. In order to restore a bug-to-bug compatible system, we describe the migration from CentOS 8 to AlmaLinux 8.
We have migrated a couple of (virtual) servers from CentOS 8 to AlmaLinux 8 using this howto. Nevertheless we advise you to be careful and create a backup or snapshot. Use the following instructions at your own risk.
Update to CentOS 8.5
You can skip this step if you're already running CentOS 8.5 including the latest updates. This example shows how to update to the latest release, which does not work out-of-the-box as the mirror servers providing the necessary rpm packages are not online anymore. Therefore we change the repository URLs to use the CentOS archive vault.centos.org and update the system afterwards.
Startingpoint in this example is CentOS 8.0.1905:
[root@server ~]# cat /etc/centos-release CentOS Linux release 8.0.1905 (Core)
Update repository URLs:
[root@server ~]# sed -i -r 's|^(mirrorlist.+)$|#\1|g; s|^#baseurl=http://mirror.centos.org/\$contentdir/\$releasever/|baseurl=https://vault.centos.org/8.5.2111/|g' /etc/yum.repos.d/CentOS-*.repo
[root@server ~]# dnf clean all
61 files removed
[root@server ~]# dnf update
CentOS-8 - AppStream 7.2 MB/s | 8.4 MB 00:01
CentOS-8 - Base 38 MB/s | 4.6 MB 00:00
CentOS-8 - Extras 129 kB/s | 10 kB 00:00
Extra Packages for Enterprise Linux 8 - x86_64 8.0 MB/s | 14 MB 00:01
Last metadata expiration check: 0:00:01 ago on Wed 03 Jul 2024 04:10:48 PM CEST.
Dependencies resolved.
==================================================================================================================
Package Arch Version Repository Size
==================================================================================================================
Installing:
centos-linux-release noarch 8.5-1.2111.el8 BaseOS 22 k
replacing centos-release.x86_64 8.0-0.1905.0.9.el8
kernel x86_64 4.18.0-348.7.1.el8_5 BaseOS 7.0 M
kernel-core x86_64 4.18.0-348.7.1.el8_5 BaseOS 38 M
kernel-modules x86_64 4.18.0-348.7.1.el8_5 BaseOS 30 M
Upgrading:
annobin x86_64 9.72-1.el8_5.2 AppStream 111 k
apr x86_64 1.6.3-12.el8 AppStream 129 k
bind-libs x86_64 32:9.11.26-6.el8 AppStream 174 k
bind-libs-lite x86_64 32:9.11.26-6.el8 AppStream 1.2 M
bind-license noarch 32:9.11.26-6.el8 AppStream 102 k
bind-utils x86_64 32:9.11.26-6.el8 AppStream 451 k
...
Transaction Summary
==================================================================================================================
Install 28 Packages
Upgrade 391 Packages
Total download size: 504 M
Is this ok [y/N]: y
Downloading Packages:
...
Complete!
Migrate CentOS 8.5 to AlmaLinux 8
The first step is to change the repository URLs (again), then import the AlmaLinux RPM-GKG-Key to verify rpm packages and starting the migration using almalinux-deploy.sh afterwards. This script is provided by AlmaLinux via GitHub.
[root@server ~]# sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[baseos\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/BaseOS/$basearch/os' /etc/yum.repos.d/CentOS-Linux-BaseOS.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[appstream\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/AppStream/$basearch/os' /etc/yum.repos.d/CentOS-Linux-AppStream.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[cr\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/ContinuousRelease/$basearch/os' /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[devel\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/Devel/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Devel.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[extras\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/extras/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Extras.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[fasttrack\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/fasttrack/$basearch/os' /etc/yum.repos.d/CentOS-Linux-FastTrack.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[ha\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/HighAvailability/$basearch/os' /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[plus\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/centosplus/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Plus.repo sed -i -e '/mirrorlist=http:\/\/mirrorlist.centos.org\/?release=$releasever&arch=$basearch&repo=/ s/^#*/#/' -e '/baseurl=http:\/\/mirror.centos.org\/$contentdir\/$releasever\// s/^#*/#/' -e '/^\[powertools\]/a baseurl=https://mirror.rackspace.com/centos-vault/8.5.2111/PowerTools/$basearch/os' /etc/yum.repos.d/CentOS-Linux-PowerTools.repo [root@server ~]# dnf clean all 30 files removed [root@server ~]# rpm --import https://repo.almalinux.org/almalinux/RPM-GPG-KEY-AlmaLinux [root@server ~]# curl -O https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh [root@server ~]# bash almalinux-deploy.sh Check root privileges OK Check centos-8.x86_64 is supported OK Download RPM-GPG-KEY-AlmaLinux OK Import RPM-GPG-KEY-AlmaLinux to RPM DB OK Download almalinux-release package OK Verify almalinux-release package OK Your OS is supported OK warning: /etc/yum.repos.d/CentOS-Linux-PowerTools.repo saved as /etc/yum.repos.d/CentOS-Linux-PowerTools.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-Plus.repo saved as /etc/yum.repos.d/CentOS-Linux-Plus.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo saved as /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-FastTrack.repo saved as /etc/yum.repos.d/CentOS-Linux-FastTrack.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-Extras.repo saved as /etc/yum.repos.d/CentOS-Linux-Extras.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-Devel.repo saved as /etc/yum.repos.d/CentOS-Linux-Devel.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo saved as /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-BaseOS.repo saved as /etc/yum.repos.d/CentOS-Linux-BaseOS.repo.rpmsave warning: /etc/yum.repos.d/CentOS-Linux-AppStream.repo saved as /etc/yum.repos.d/CentOS-Linux-AppStream.repo.rpmsave Remove OS specific rpm packages OK Verifying... ######################################## Preparing... ######################################## Updating / installing... almalinux-release-8.10-1.el8 ######################################## Install almalinux-release package OK Remove centos-logos-httpd packages OK Install almalinux-logos-httpd packages OK Backup of alternatives is done OK Last metadata expiration check: 0:00:13 ago on Wed 03 Jul 2024 04:45:55 PM CEST. NetworkManager.x86_64 1:1.40.16-15.el8_9 baseos NetworkManager-libnm.x86_64 1:1.40.16-15.el8_9 baseos NetworkManager-team.x86_64 1:1.40.16-15.el8_9 baseos NetworkManager-tui.x86_64 1:1.40.16-15.el8_9 baseos acl.x86_64 2.2.53-3.el8 baseos ... Complete! Run dnf distro-sync -y OK Restoring of alternatives is done OK Generating grub configuration file ... done All Secure Boot related packages which were not released by AlmaLinux are reinstalledOK Migration to AlmaLinux is completed
After almalinux-deploy.sh has successfully completed the migration, you should reboot the server. You can also verify that the new kernel for AlmaLinux 8.10 in this case is the new grub default:
[root@server ~]# grubby --info DEFAULT | grep AlmaLinux title="AlmaLinux (4.18.0-553.8.1.el8_10.x86_64) 8.10 (Cerulean Leopard)" [root@server]# cat /etc/almalinux-release AlmaLinux release 8.10 (Cerulean Leopard)