AlmaLinux8

v1 : Starting template for migrating from CentOS8 because it has reached its end of life. AlmaLinux serves as a direct binary drop-in replacement for CentOS8.

Migration guidelines for upgrading or migrating CentOS8 templates

This information comes from the official AlmaLinux deployment guide, available at https://github.com/AlmaLinux/almalinux-deploy . Do check the latest version there; the text below is copied as of 29/3/2022 for reference.

We're providing this as a guide for the community, but please note that we cannot assume responsibility for any errors or issues that may arise from following these notes.

almalinux-deploy

A migration tool for converting Enterprise Linux to AlmaLinux.

How to use

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

Your system needs to be running CentOS 8.4 or 8.5 for conversion. While updating to 8.5 is suggested before the migration, it's not mandatory if you are already on at least 8.4. After applying updates, a reboot is advisable if your system received new packages.
```
sudo dnf update -y
sudo reboot
```

Since the CentOS 8 mirrorlists went offline on 31 January 2022, to successfully run dnf update -y, you'll need to modify your dnf config files to point to a working mirror. You can use the following sed commands to restore dnf to a working state, allowing you to update to 8.5 and then 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, you can use the -f flag (i.e., sudo bash almalinux-deploy.sh -f) to handle this automatically.

Back up your system. We haven't tested every possible scenario, so there is always a risk that something might go wrong. Having a backup gives you a restore point.

Download the almalinux-deploy.sh script:

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

Run the script and check the output for any errors:

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

A reboot is recommended to boot into the AlmaLinux kernel:
```
sudo reboot
```

Verify that your system was successfully converted:

# 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)"

We appreciate your choice of AlmaLinux!