AlmaLinux8

v1: This initial template is for migrating from CentOS8 now that it's reached end-of-life. Almalinux acts as a direct binary replacement for CentOS8.

Migration guidance for users planning to upgrade or migrate their CentOS8 templates

The content below is extracted from AlmaLinux’s official migration guide, available at https://github.com/AlmaLinux/almalinux-deploy. We recommend checking the link for the most up-to-date version; the instructions provided here are current as of 29/3/2022.

These notes are offered as a helpful resource for our community, but we accept no liability for any errors or problems that may arise from following them.

almalinux-deploy

An EL to AlmaLinux migration tool.

Usage

To convert your EL8 OS to AlmaLinux, follow these steps:

You'll need CentOS 8.4 or 8.5 to migrate to AlmaLinux. It's a good idea to upgrade to 8.5 first, though if you're already on 8.4 that's acceptable. After applying updates, restarting is advisable if your system pulled in new packages.
```
sudo dnf update -y
sudo reboot
```

Since January 31, 2022, the CentOS 8 mirrorlists have been taken offline. To run dnf update -y successfully, you'll need to modify your dnf configuration to use an active mirror. The sed commands below can be used to quickly put dnf back into a working state, enabling you to update to 8.5 and then proceed to AlmaLinux.

sudo 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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-BaseOS.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-AppStream.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Devel.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Extras.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-FastTrack.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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/$basearch/os' /etc/yum.repos.d/CentOS-Linux-Plus.repo
sudo sed -i -e '/mirrorlist=http://mirrorlist.centos.org/?release=$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

Alternatively, using the -f flag (i.e., sudo bash almalinux-deploy.sh -f) will take care of this automatically.

Create a backup of your system. Since not every scenario has been tested, there is a chance something might go awry; having a backup ensures you can restore if needed.

Retrieve the almalinux-deploy.sh script:

$ curl -O https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh

Execute the script and inspect the output for any errors:

$ sudo bash almalinux-deploy.sh
  ...
  Migration to AlmaLinux is completed

A reboot is advisable so you can start using the AlmaLinux kernel:
```
sudo reboot
```

Verify that the conversion completed successfully:

# confirm release version
$ cat /etc/redhat-release
AlmaLinux release 8.5 (Arctic Sphynx)

# confirm the system boots AlmaLinux kernel by default
$ sudo grubby --info DEFAULT | grep AlmaLinux
title="AlmaLinux (4.18.0-348.el8.x86_64) 8.5 (Arctic Sphynx)"

Thanks for going with AlmaLinux!