Microsoft has traveled a long road, from warring with Linux to shipping its own free distribution. The company has released Azure Linux 4.0 to the public. You can download and use it now. However, the product targets cloud servers and container workloads on Azure, not home laptops or a familiar desktop, as Windows Latest reports.
From “Cancer” to Its Own Distro
The story looks especially striking against an old remark. Twenty-five years ago, former Microsoft chief Steve Ballmer called Linux a “cancer” for intellectual property.
Now Microsoft itself maintains an open Linux distribution. It signs packages, ships security updates, and offers the system as part of its own cloud platform.
Where Azure Linux Came From
Azure Linux did not appear from nothing. The project started in 2019 under the name CBL-Mariner. It grew as an internal, lightweight system for Microsoft’s infrastructure.
By 2022, the distribution already served Azure workloads. These included Azure Kubernetes Service, Azure SQL, and Azure Cosmos DB. Later, LinkedIn moved its infrastructure to Azure Linux 3. Databricks then migrated more than 100,000 virtual machines and over a million CPU cores, with no failures visible to customers. Microsoft settled on the name Azure Linux in March 2024.
What Changed in Version 4.0
The main change in version 4.0 concerns the distribution’s foundation. Previously, Microsoft engineers assembled the system package by package and wrote their own specifications.
Now Azure Linux builds on a Fedora 43 snapshot with a set of declarative overlays. Moreover, every deviation from the upstream base appears in a public GitHub repository. This approach simplifies review of changes. It also brings the system’s behavior closer to the Fedora and Red Hat ecosystem.
Not Ubuntu or Fedora for Everyday Users
For a regular user, Azure Linux 4.0 looks nothing like Ubuntu or Fedora. The base image ships without a graphical interface, a desktop, an audio subsystem, or a familiar installer.
After launch, the user lands in a Bash console. Even creating an account during setup remains optional. Because of that, careless configuration can end with no way to log in.
Deliberate Minimalism
Microsoft chose this minimalism on purpose. Fewer packages in the base image mean a smaller attack surface. They also mean fewer components to update when patching vulnerabilities.
Therefore, Microsoft promotes Azure Linux as a system for servers, virtual machines, and containers on Azure. It is not a universal replacement for Ubuntu, Fedora, or Red Hat Enterprise Linux on any hardware. You can technically run the distro outside Azure. Yet official support does not cover that mode.
What’s Inside Azure Linux 4.0
Azure Linux 4.0 bundles a modern stack. It includes the Linux 6.18 LTS kernel, the dnf5 package manager, glibc 2.42, and systemd 258. In addition, it ships Python 3.14 with a JIT compiler and OpenSSL 3.5 with post-quantum cryptography support.
However, FIPS 140-3 certification is not finished yet. As a result, the distro does not yet replace certified RHEL builds for organizations with strict compliance requirements.
Azure Container Linux, the Companion
Alongside Azure Linux, Microsoft develops Azure Container Linux. The two products are easy to confuse, but their purposes differ.
Azure Linux 4.0 suits cloud servers and allows package installation. Azure Container Linux, by contrast, uses an immutable, read-only image built for Kubernetes nodes. In that case, an update replaces the entire image and can roll back automatically on failure.
Why Microsoft Built Its Own Linux
For Microsoft, an in-house Linux distribution is no symbolic gesture. Instead, it forms part of the cloud strategy. Linux already accounts for a large share of workloads on Azure. Meanwhile, third-party distributions send support and subscription revenue to other vendors.
Azure Linux lets Microsoft control the operating system, the supply chain, package signing, and SBOM documents within one platform. For ordinary Windows or Ubuntu users, the release changes little. For the cloud market, however, the signal is clear. Microsoft no longer merely runs Linux on Azure. It now offers its own Linux system as a base infrastructure layer.
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