AlmaLinux8

v1: This initial template is provided for migrating away from the CentOS8 template now that it has reached end-of-life. AlmaLinux serves as a binary-compatible drop-in replacement for CentOS8.

Guidance for users looking to upgrade or migrate their CentOS8 templates

The following content is drawn from AlmaLinux's official guide, available at https://github.com/AlmaLinux/almalinux-deploy. We encourage you to check the link for the most up-to-date version; the text below is reproduced as a snapshot for reference (29/3/2022).

This guidance is shared for the benefit of our community, but we accept no liability for any errors or issues that may arise from following these notes.

almalinux-deploy

An EL to AlmaLinux migration tool.

Usage

To convert your EL8 operating system to AlmaLinux, follow these steps:

You‘ll need CentOS 8.4 or 8.5 as your starting point. We advise upgrading to 8.5 before proceeding, though it’s not mandatory if you're already on at least 8.4. If your system installs new updates, a reboot is suggested thereafter.
```
sudo dnf update -y
sudo reboot
```

Starting from 31 January 2022, the CentOS 8 mirror lists went offline. To run dnf update -y successfully, you must adjust your dnf configuration files to reference a working mirror. The sed commands below can help you quickly restore dnf to a functioning state, allowing an update to 8.5 and then 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, you can pass the -f flag (e.g., sudo bash almalinux-deploy.sh -f) to have the script take care of this automatically.

Take a full backup of your system. Since not every scenario has been tested, there‘s a chance of unexpected behaviour. Having a backup gives you a restore point if needed.

Fetch the almalinux-deploy.sh script:

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

Execute the script and review its output for any errors:

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

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

Confirm that the conversion was successful:

# check release file
$ cat /etc/redhat-release
AlmaLinux release 8.5 (Arctic Sphynx)

# check that 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 choosing AlmaLinux!