This step by step tutorial explains how to migrate to AlmaLinux 8 from CentOS 8 using Almalinux-deploy script. Using Almalinux-deploy script, we can easily convert CentOS machines (hopefully other Enterprise Linux systems) to AlmaLinux.
It is written in Bash and the source code is available in GitHub. Now let us go ahead and migrate from CentOS to AlmaLinux with almalinux-deploy script.
If you don't want to upgrade but want to do a fresh AlmaLinux installation, refer the following guide:
Migrate to AlmaLinux from CentOS 8 using almalinux-deploy script
A word of caution:
As usual, backup important data from your CentOS system before starting AlmaLinux migration task. I tested this script in a freshly installed CentOS 8 virtual machine. My VM doesn't has any data and it is a server edition with minimal installation. It worked just fine without any issues as expected.
Step 1: Update your CentOS system to latest available version as root or sudo user:
$ sudo dnf update
Step 2: Reboot your system to apply the updates:
$ sudo reboot
Let us check the current CentOS 8 version:
$ cat /etc/redhat-release CentOS Linux release 8.3.2011
Yes, it is the latest version!
Step 3: Download the almalinux-deploy script using command:
$ curl -O https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh
Step 4: Go to the location where you downloaded the script and run the script to start Almalinux migration:
$ sudo bash almalinux-deploy.sh
This command will install some new packages, upgrade and downgrade some existing packages, reinstall a few packages and uninstall some packages.
This will take a couple minutes depending upon the Internet connection speed and the total number of installed packages in your CentOS system.
Sample output:
Check root privileges OK
Check Secure Boot disabled 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
Remove centos-linux-release package OK
Remove centos-gpg-keys package OK
Remove centos-linux-repos package OK
Verifying… ################################# [100%]
Preparing… ################################# [100%]
Updating / installing…
1:almalinux-release-8.3-4.el8 ################################# [100%]
Install almalinux-release package OK
determining the fastest mirror (55 hosts).. done. [=== ] --- B/s | 0 B --:-- ETA
AlmaLinux 8 - BaseOS 125 kB/s | 3.4 MB 00:27
AlmaLinux 8 - AppStream 155 kB/s | 6.8 MB 00:44
AlmaLinux 8 - PowerTools 589 kB/s | 2.1 MB 00:03
AlmaLinux 8 - Extras 3.3 kB/s | 3.6 kB 00:01
Dependencies resolved.
Package Architecture Version Repository Size
Upgrading:
NetworkManager x86_64 1:1.26.0-13.el8_3 baseos 2.4 M
NetworkManager-libnm x86_64 1:1.26.0-13.el8_3 baseos 1.7 M
NetworkManager-team x86_64 1:1.26.0-13.el8_3 baseos 141 k
NetworkManager-tui x86_64 1:1.26.0-13.el8_3 baseos 319 k
dbus x86_64 1:1.12.8-12.el8_3 baseos 40 k
dbus-common noarch 1:1.12.8-12.el8_3 baseos 44 k
dbus-daemon x86_64 1:1.12.8-12.el8_3 baseos 239 k
dbus-libs x86_64 1:1.12.8-12.el8_3 baseos 182 k
dbus-tools x86_64 1:1.12.8-12.el8_3 baseos 84 k
device-mapper x86_64 8:1.02.171-5.el8_3.2 baseos 372 k
[...] 
If the migration is successful, you will see the following message:
[...] Complete! Run dnf distro-sync -y OK
Step 5: Run the following command to synchronize installed packages to the latest available versions.
$ sudo dnf distro-sync -y
Step 6: Reboot your system:
$ sudo reboot
Now your system will boot into the newly migrated AlmaLinux system:
Step 7: Login to your AlmaLinux system and check its version:
$ cat /etc/redhat-release AlmaLinux release 8.3 (Purple Manul)
Congratulations! AlmaLinux migration is successful!!
Step 8: You could have used the word "centos" in hostname and username. Simply change them wherever necessary to reflect AlmaLinux.
I am going to update the hostname:
$ sudo hostnamectl set-hostname almalinux8
Replace almalinux8 with your preferred hostname in the above command.
Step 9: Log out and log back in to verify if the changes have been made:
$ hostname almalinux8
Yes, the changes are updated!
Check that the system boots AlmaLinux kernel by default using command:
$ sudo grubby --info DEFAULT | grep AlmaLinux
Sample output:
title="AlmaLinux (4.18.0-240.15.1.el8_3.x86_64) 8.3 (Purple Manul)"
All good! Start using your AlmaLinux!!
We also have published an unofficial AlmaLinux migration method. If you're interested to know how to do it, take a look at the following link:
Migrate CentOS 7 to Any Enterprise Linux 8 With ELevate
Please note that the almalinux-deploy script will only convert CentOS 8 version to AlmaLinux 8. If you are running older versions like CentOS 7.x or 6.x, this script will not help.
Thankfully, the AlmaLinux developers have create a tool called ELevate to migrate CentOS 7 to any Enterprise Linux 8.x version.
ELevate is an open source migration tool developed by AlmaLinux team. It allows you to migrate between major versions of RHEL-based distributions from 7.x to 8.x version. For more details, refer the following guide.
Hope this helps.
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