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Sovereign Cloud Stack Release 8 released

9 April 2025

Sovereign Cloud Stack software released in version 8

Europe, 9 April 2025: Risk avoidance and achieving digital sovereignty with Sovereign Cloud Stack Release 8

While funding for the Sovereign Cloud Stack (SCS) project by the Federal Ministry for Economic Affairs and Climate Protection expired in December 2024, committed companies, organisations and an active open source community have been working on maintaining and further developing the SCS standards, the SCS reference implementation and also building up operational knowledge. Collaboration on the further development of the software has led to the release of R8 of the SCS software.

Increasing relevance of digital sovereignty

When the Sovereign Cloud Stack Initiative was launched at the end of 2019, the goal was to empower operators and users of cloud technology with control, value creation and innovation capabilities. With a clear concept of the various aspects of digital sovereignty, SCS was formed with the aim of covering all aspects. SCS gives IT departments and providers control over data (data sovereignty), users the ability to easily switch providers (switchability), the opportunity to help shape the technology (technological sovereignty) and the ability to build knowledge about the use and operation of such platforms. These issues were very important at the time, but were only considered important by a small group of people who were concerned about the structure of our IT market. Since then, this issue has become visible to more and more people, leading, among other things, to the emergence of so-called „sovereign clouds“ — typically offerings that merely attempt to solve the problem of data sovereignty. However, there are also increasingly broader approaches, e.g. in Germany via networking in the area of digital public infrastructure (DPI) with, among others, the Sovereign Tech Agency, or globally, e.g. with the Govstack project and the UN initiative OSPOs for Good. With the EuroStack white paper, the discussion has now reached Brussels, and SCS is happy to contribute to the discussions there, but also — unlike many others — with open standards and technologies.

Avoiding risks during the upgrade

SCS makes it easy for operators to stay up to date with the latest software, which is constantly being developed by the SCS community, but above all by the many upstream projects on which SCS is based and to which SCS contributes. The new release was built with the help of a robust mechanism that continuously integrates and tests software (CI/CD) and records dependencies (e.g. for creating a software bill of materials, SBOM), performs integration tests (for both new installations and upgrades) and security tests. The software for this continuous verification is part of the SCS reference implementation and can be used by providers according to their needs. The SCS community itself operates infrastructure to ensure that the SCS software does not break unnoticed and that the build and test processes always function reliably. The coordination and networking of operators has also led to smooth upgrades for operators. SCS thus helps to avoid the trap of operators being stuck on old versions with all the fragmentation and security problems that this would entail. In addition to support from the SCS community, the companies that are responsible for the bulk of SCS's further development offer commercial support and maintenance services for the completely open SCS software in order to secure the operation of productive environments.

Current software

The SCS R8 reference implementation contains the latest versions of key upstream projects. For some components, operators now have the choice of which version to use. They can stick with the old Ubuntu 22.04 LTS version (instead of the planned 24.04 LTS version), OpenStack 2024.1 (instead of 2024.2) and Ceph Quincy (instead of Reef). SCS now allows you to skip the 20xx.2 OpenStack versions and upgrade directly from the last spring release 20xx.1 (SLURP = skip-level update release process). Traditionally, you had to go through every intermediate step.

At the container level, R8 contains the latest version of Kubernetes and Kubernetes Cluster API. The latest version of the OpenStack Provider (CAPO) now uses the OpenStack Resource Controller (ORC), eliminating the need for the Cluster Stack Provider for OpenStack (CSPO) component that was previously shipped with SCS Cluster Stacks. The SCS cluster stacks now use multi-stage add-on support, which ensures that even with complex dependencies in Kubernetes upgrades, all components (such as CCM (Cloud Controller Manager), CNI (Cloud Networking Integration) and CSI (Cloud Storage Integration)) are executed in the correct order to avoid cluster downtime. Users can choose between different current Kubernetes versions and also upgrade their clusters.

There have also been innovations in the operating tools: the registry (used by harbor) has been updated and the container monitoring solution has been upgraded to the latest version. Both have already been in productive use in the project for several weeks.

„We are seeing a significant increase in demand for sovereign cloud solutions. By relying on SCS, we are able to offer a reliable and powerful platform without vendor lock-in,“ says Freerk-Ole Zakfeld, Head of Cloud Operations at ScaleUp Technologies. ScaleUp is the latest addition to the growing group of SCS operators.

About the Sovereign Cloud Stack Project

The Sovereign Cloud Stack (SCS) project is an open-source project maintained by the SCS community, which consists of companies, users and developers and is governed by an elected project board. An international ecosystem of two dozen companies contributes to the success of SCS, accompanied by the SCS Standards Forum at the Open Source Business Alliance (OSBA). There, open standards for modern, federable open-source cloud and container platforms are developed and disseminated, avoiding technical dead ends and lock-in. Many companies that contribute to the SCS community continue to develop the SCS reference implementation in an open development process, using proven open-source components and thus creating regular and predictable releases. At the same time, operational experience and practical knowledge are made transparent in order to minimise the difficulties involved in operating reliable and secure cloud services. More than half a dozen public cloud operators use SCS in production to offer truly sovereign and GDPR-compliant cloud services. Further SCS clouds are under construction, including a government cloud in Guinea and a private cloud in the UN's data centres (UNICC). SCS also contributes to GovStack Initiative and to Gaia-X at and is a Gaia-X flagship project. SCS was funded by the Federal Ministry for Economic Affairs and Climate Protection (BMWK) from 2021 to 2024.