Microsoft has announced the public preview of Azure Linux 4.0, giving users an early look at the next major version of its Linux distro built specifically for Azure workloads.
The release follows the previously confirmed move to a Fedora-derived foundation, which represented a major architectural shift for Azure Linux 4.0. That change brought the distribution closer to Fedora’s packaging ecosystem while retaining Microsoft’s Azure-specific customization layer.
The distro, previously known as CBL-Mariner, is Microsoft’s own open-source Linux distribution for cloud infrastructure. And now, Azure Linux 4.0 is available for public evaluation. Formerly limited to development, it can now be tested ahead of its stable release. The distro is available through the Azure Marketplace and can be deployed on Azure Virtual Machines and VM Scale Sets.
Microsoft says Azure Linux 4.0 is intended for Azure workloads, including virtual machines, virtual machine scale sets, container images, and Kubernetes-related use cases. In practice, this places it in the same niche category as cloud-provider Linux systems such as Amazon Linux, but with Microsoft’s focus centered on Azure integration, lifecycle management, and operational consistency.
The Fedora-derived base is still one of the most important technical changes in Azure Linux 4.0. Instead of maintaining a more isolated package base, Microsoft now pulls sources directly from Fedora Linux and applies targeted overlays to meet Azure-specific requirements. The distribution remains RPM-based and continues to rely on familiar RPM tooling.
However, there is an important point to understand. Azure Linux 4.0 is not simply a rebadged Fedora system. Microsoft is using Fedora as a foundation while keeping control over the final package set, configuration, security posture, and Azure integration points. So, it is a Linux distribution shaped around Microsoft’s cloud platform rather than a community desktop or general-purpose server distro.
Moreover, support for Azure Linux 4.0 is limited to Azure environments. While images and ISOs can be tested elsewhere, the distribution is not supported for bare-metal, other cloud platforms, or desktop use.
Finally, keep in mind that Microsoft emphasizes that this version is for evaluation only and is not production-ready.
