AlmaLinux Decided to Drop 1:1 Compatibility with RHEL

AlmaLinux will now only be Application Binary Interface (ABI) compatible with Red Hat Enterprise Linux due to Red Hat's actions.

AlmaLinux emerged as a prominent alternative for users seeking a stable, community-driven operating system after CentOS shifted its focus to CentOS Stream, a rolling-release distribution.

The distro quickly gained recognition as a suitable, enterprise-ready replacement for CentOS, offering a stable and secure environment that mirrored RHEL.

Unfortunately, this did not sit well with IBM/Red Hat, who did the unthinkable to eliminate their direct competitors in the enterprise Linux industry, AlmaLinux, Rocky Linux, and Oracle Linux.

Going against all moral norms and acting against the values of the whole open source community in general, under threat of legal consequences, Red Hat restricted access to their source code using a clause in Red Hat’s Software Subscriptions preventing its redistribution.

In response, the team behind AlmaLinux has decided to shift its focus from this to being 1:1 compatible with RHEL towards achieving Application Binary Interface (ABI) compatibility.

AlmaLinux Will Be Only ABI Compatible with RHEL

AlmaLinux 9.2
AlmaLinux 9.2

In a message on the project’s blog pages titled “The Future of AlmaLinux is Bright,” the distro announced the following:

After much discussion, the AlmaLinux OS Foundation board today has decided to drop the aim to be 1:1 with RHEL. AlmaLinux OS will instead aim to be Application Binary Interface (ABI) compatible.

So far, so good, but the first question that comes to mind is what this means and what the difference is. We immediately explain.

When a Linux distribution claims to be 1:1 compatible with another distribution, it aims to replicate the reference distribution’s exact functionality, behavior, and binary compatibility.

Furthermore, 1:1 compatibility also means bug-to-bug compatibility. In other words, the moment a patch is applied to the upstream, in the case of RHEL, the downstream, AlmaLinux, immediately implements it on itself.

In practice, the only difference between RHEL and AlmaLinux has been the removal of RHEL’s branding packages. However, this no longer be the case.

Transitioning to the Application Binary Interface (ABI) model means that AlmaLinux aims to ensure that applications developed for RHEL will seamlessly run on its distribution without requiring any modifications or additional effort from users.

But at the same time, AlmaLinux will now be able to implement its bug fixes (and, if necessary, features) in its distribution in addition to those available for Red Hat Enterprise Linux.

What Does This Mean for the End User?

There is no difference from a purely technical standpoint for the end user. All applications and services will continue functioning as before, requiring no extra changes.

Any software available for Red Hat Enterprise Linux will be able to be installed, configured, and run on AlmaLinux just like on RHEL.

The main differences are mainly on the development side regarding how the distribution is built because transitioning from 1:1 to ABI compatibility necessitates some changes, which AlmaLinux is already working on.

Bottom Line

With AlmaLinux taking a bold step towards only being ABI compatible with RHEL dropping 1:1, the enterprise Linux community and all open-source advocates eagerly await further developments and the potential advantages this decision may bring.

At the same time, the distro reaffirmed its commitment to open-source values, saying that despite the situation, Alma will continue to contribute its changes to the upstream Fedora and CentOS Stream distributions.

While all of these changes open up a lot of opportunities, we want to be clear about the fact that we are still dedicated to being good open source citizens. We’ll continue to contribute upstream in Fedora and CentOS Stream and to the greater Enterprise Linux ecosystem, just as we have been doing since our inception, and we invite our community to do the same!

Finally, due to IBM/Red Hat’s actions, this is expected to be the model that the other two major RHEL replacements, Rocky Linux and Oracle Linux, will also adopt. As always, we will keep you updated on any changes.

Bobby Borisov

Bobby Borisov

Bobby, an editor-in-chief at Linuxiac, is a Linux professional with over 20 years of experience. With a strong focus on Linux and open-source software, he has worked as a Senior Linux System Administrator, Software Developer, and DevOps Engineer for small and large multinational companies.

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