CentOS7 End of Life Migration

Operating systems at Nikhef

CentOS has long been a favourite operating system (OS) for research and academia because it was free and open source. However, Red Hat (the current maintainer of the CentOS project) announced that they will be discontinuing support for CentOS 7 distribution in June 2024, and CentOS Stream 8 in May 2024 [1]. This means that Nikhef will need to migrate all its systems away from the no-longer supported CentOS systems to supported OS distributions (such as Alma Linux 9). We have decided to follow CERN and deploy Alma Linux 9 for all user-facing services, allowing some continuity for work.

This is unfortunately a disruptive migration but fully necessary to maintain security for users and the institute.

The CT department maintains the computing systems, storage and services at Nikhef. Nikhef’s user-facing services (such as login.nikhef.nl and the Stoomboot cluster) will be migrated to Alma Linux 9 [2] before June 2024. In order for people to test their scripts and analysis work, we are setting up Alma Linux 9 test systems. These systems will be ready by 15 February. We want to work with you during this migration to help solve issues that may arise. We can be reached in the office (H232), via email through helpdesk@nikhef.nl, and the CT user office hours.

CentOS 7 End-of-Life

The operating system of choice for the last decade was CentOS 7, a 'free' rebuild of Red Hat Enterprise Linux 7 (RHEL7). It closely follows the upstream release to be bug-for-bug compatible with RHEL7.

Red Hat claims to support its Enterprise Linux releases for ten years; five years of full support and five years maintenance support. The maintenance support of RHEL7 is due to end on 30 June 2024.

That means after June 2024, any software vulnerabilities found in the operating system will not be fixed by Red Hat, and Nikhef can no longer risk using CentOS 7.

What about CentOS 8?

We have seen the evolution of RHEL since version 3, and free rebuilds like CentOS and Scientific Linux follow in lock step. This changed when, firstly, Red Hat acquired CentOS and folded it into its own operation and, secondly, it declared that CentOS would only be available as CentOS Stream, acting as the developer (or upstream) side of RHEL. Support for CentOS 8 ended already after 2021. There will not be a CentOS 9 at all.

After careful consideration in the computing science communities, the idea of using CentOS Stream as a viable operating system for production use was largely rejected, and most labs moved to using one of the new free rebuilds that had sprung up. Nikhef opts to install Alma Linux 9 as a replacement.

Alma Linux

The Alma Linux project aims for binary compatibility with RHEL. Since RHEL9 is already released, it makes sense to skip the intermediate version 8. This means that for most systems we are looking at an upgrade from CentOS 7 to Alma Linux 9.

Support for the CentOS 7 toolstack beyond June 2024

We foresee that some people who are in the final stages of their research projects depend on the CentOS 7 toolstack, such as compiler versions, Python versions, and other library versions that are no longer going to work after upgrading to Alma Linux 9. We would like to know how many people would face serious problems as a consequence of the upgrade. We may be able to provide access to the CentOS 7 stack via container images, but we do not have a fully transparent way to support that at this moment.

OS Upgrade plan

Upgrading the systems will happen gradually, starting with one of the login servers, one of the interactive stoomboot nodes, and a few worker nodes. There will be a period of testing and evaluation, where we encourage feedback from as many people as are willing to try things out.

After a period of ironing out the kinks (which will hopefully be few!) more and more worker nodes will be upgraded, reducing the available capacity of CentOS 7 systems to a minimum. The default choice of operating system for the Stoomboot queues will be switched to Alma Linux 9.

We will monitor the relative use and encourage the stragglers to move. This would be the time when people who really have difficulty moving the new OS will be engaged to find a workable solution. We may keep some limited capacity available until June but certainly not beyond that date.

Upgrade time table

The upgrade time table is still being worked on. We aim to have everything done by May to have enough slack in the schedule before support ends on 30 June 2024.

	15 February	1 May	15 May	30 May
Trial upgrade for login2.nikhef.nl, stbc-i3.nikhefnl, some worker nodes in the Stoomboot cluster (accessible via a queue)	Planned
End of trial and testing run		Planned
Alma9 becomes default			Planned
End of CentOS 7 on all systems				Planned