A month ago, we reported that Microsoft was targeting Fedora as the base for the next version of its Azure Linux, designed to support the company’s cloud infrastructure. And now this has officially been confirmed.
Microsoft describes the upcoming Azure Linux 4 as “an open-source Linux distribution built and optimized for Azure, with sources derived from Fedora Linux.”
Previously known as CBL-Mariner, the distro will continue to target Azure workloads such as virtual machines, containers, and bare-metal platforms, but the big difference from previous versions is that its packaging is now directly linked to the Fedora ecosystem.
In other words, with Azure Linux 4, Microsoft is adopting a Fedora-based development model while maintaining Azure-specific customization. Importantly, Azure Linux 4 remains an RPM-based distribution, but it is still in development and not yet available for download. Microsoft advises users to deploy Azure Linux 3 in the meantime.
The repository notes that the system is defined using TOML configuration files and targeted overlays on Fedora Linux packaging sources. Microsoft states these overlays are limited to prevent unnecessary divergence from upstream Fedora.
The repository includes automatically generated RPM spec files, created by applying Azure Linux’s overlay to Fedora’s upstream packaging sources. These files are checked in for transparency and auditing, and standard RPM tools such as mock, rpmbuild, and Koji are used for building.
This provides Azure Linux 4 with a familiar RPM-based package ecosystem while enabling Microsoft to maintain Azure-specific enhancements in security, compliance, integration, kernel development, lifecycle management, and cloud operations.
For additional details, visit the Azure Linux 4 GitHub repo.
