CentOS 8 Migration

I have a pipeline which creates live images to network boot different systems. Historically this has been based on CentOS. A little while ago I moved it to CentOS 8 because I had some newer hardware that was not supported on the older kernel of 7. Everything was working well until recently when CentOS 8 went end of life, and I could no longer rely on the CentOS 8 Docker containers.

The journey began for a new EL8 system. I wanted to keep on EL8 instead of switching to Streams because all the other systems I had running were EL8 (CentOS 8 or RHEL8), and I wanted to keep compatibility. At the same time, I didn’t want to do a new build of the image, have things break, and not realize it was because of a CentOS Streams change upstream. I also used the CentOS 8 docker container which seems to have been pulled, so that forced me to do this change now.

My first thought was Oracle Linux. It has been around for a while, is ALMOST drop in compatible, and can be used without going and getting licenses (RHEL). (There are some small silly things like instead of “epel-release” the package is “oracle-epel-release-el8”) This lead to nothing but issues. I replaced all the repos I had in the image creation stage with Oracle Linux ones, then every build I got a ton of “nothing provides module(platform:el8)” lines for any package that used yum/dnf modules. I spent a chunk of time on this, finding no real answers, and one Oracle support page that looked like it could help saying I needed to buy a support contract. Classic Oracle. At one point I thought it had something to do with Commit – rpms/centos-release – 89457ca3bf36c7c29d47c5d573a819dd7ee054fe – CentOS Git server where a line in os-release confuses dnf, but then that line was there. Also Oracle doesn’t seem to have a kickstart url repo, which is needed to do this sort of network boot. They wanted the end user to set that repo up, which may be the source of my issues. This also touched on the issue Disable Modular Filtering in Kickstart Repos – Red Hat Customer Portal, but I wasn’t even getting to a base OS setup, then I could make changes to the os and dnf for how it processes modules.

In my searches I did find this nice script to get bash variables for OS and version. https://unix.stackexchange.com/a/6348

Then I figured I would try either AlmaLinux or Rocky Linux. They both came out around when Redhat said Cent 8 was going away. Looking into both projects, they both are backed by AWS and Equinix who are big players, which made me feel a bit better about it. I had heard a bit more about Rocky and its support, so I tried that. I dropped in the new repos, and kickstart location, and everything just worked… Even things that were a issue when playing with Oracle Linux went away. For example, epel-release was once again called what it should be.

In the end so far it seems to be happy! We will see if any other small differences pop up and bite me…

Below is an example of the top of the kickstart I am using, if anyone is interested in more of how I create live images, leave a comment and I can do a post on it:

lang en_US.UTF-8
keyboard us
timezone Europe/Brussels --isUtc
auth --useshadow --enablemd5
selinux --disable
network --device=eno1 --bootproto=dhcp
skipx
part / --size 4096 --fstype ext4
part /opt --size 4096 --fstype ext4
firewall --disabled

url --url=https://download.rockylinux.org/pub/rocky/8/BaseOS/x86_64/kickstart/

# Root password
rootpw --iscrypted <Insert encrypted password here>

repo --name=baseos --baseurl=https://download.rockylinux.org/pub/rocky/8/BaseOS/x86_64/os/ --install
repo --name=extras --baseurl=https://download.rockylinux.org/pub/rocky/8/extras/x86_64/os/ --install
repo --name=appstream --baseurl=https://download.rockylinux.org/pub/rocky/8/AppStream/x86_64/os/ --install

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