Official Operating System for CTAO Software

This page provides information regarding the reference operating system (OS) valid currently for the CTAO.

Current Version

The current Officially Supported Linux Distribution in CTAO is AlmaLinux OS 9 (Linux kernel 5.14).

Alma Linux is a Linux distribution which is binary compatible to Red Hat Enterprise Linux (RHEL).

Related Information

• Migration to Alma Linux 9
• Install the Windows Subsystem for Linux on Windows

Implications

• The servers in the onsite data centers, including control, computing, management nodes, and camera servers must use the official OS. Equivalent commercial RedHat distributions may be run instead in some cases and some nodes.

• Any software running on bare metal on the onsite data centers must be compliant with the official OS.

• Bespoke software (i.e., created as IKC for the CTAO, or by the CTAO personnel as part of the CTAO software systems) must be shown to run under the official OS as part of the acceptance process. This applies to ACADA, DPPS, SUSS, SOSS, and array element software that runs on the data centers (telescope manager, bridges, camera server software, etc.). This applies to ACADA, DPPS, SUSS, SOSS, and array element software that runs on the data centers (telescope manager, bridges, camera server software, etc.).

• Containers or virtual machines created by CTAO to be run on the data centers can be:

  • Images or VMs using the official OS

  • Images produced by the computing department as base images, e.g. ACS or ACADA software development environment

  • Official Python or micromamba images (from docker hub) using other Linux distributions, if sufficiently tested on a host running the official OS.

  • Official Images or VMs with database management systems or other services, if sufficiently tested on a host running the official OS.

  • This list can be extended upon agreement with the CTAO Computing Department coordinator.

• Associated test cluster machines (for example the CTAO integration and test cluster in DESY) must use the OS or be able to run containers or VMs using the OS.

The official OS does not affect:

• Software to run on the office IT environment, commercial software running under IT

• Embedded software (PLCs, industrial PCs onboard telescopes, etc.)

• Readily available VMs or containers, that can be run as services (e.g. database management systems, web servers)

• Offsite data centers (however, they should have the capability to run TAO-provided VMs and containers that utilize the offial OS as their base image)

Future updates

Changes to the official OS are decided by the Computing Configuration Control Board (CCB), by delegation of the CTAO CCB and after consulting all affected parties.

Updates of the official operating system are planned on a regular basis, some time after a new release of Alma Linux has been made.

Developers should test their software in the integration environments as soon as possible on the next planned operating system.

OS History

For reference, here is the full table of the official operating systems over time:

From	Until	OS
2024	TBD	Alma Linux 9
—	2023	CentOS 7