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ZDNET’s key takeaways

• You can now install Azure Linux on your own server.
• Azure Linux may prove a competitor to mainstream enterprise Linux distros.
• Is Windows Server long for this world?

When my friend and Directions on Microsoft‘s Editor-in-Chief Mary Jo Foley wrote in late May that Azure Linux 4.0 would be available for bare-metal servers and virtual machines (VMs), I thought, “I’m not going to hold my breath waiting for this.” That’s a good thing because it took Microsoft until this week to fulfill the promise. 

True, Microsoft did release Azure Linux 4.0, but I assumed it would only be available for ages on Microsoft’s own Azure cloud. I mean, that’s what the distribution is designed for after all. However, Microsoft has turned Azure Linux 4.0 from internal cloud plumbing into a full‑fledged server distribution. You can now download Azure Linux ISO images and install them on your own servers and VMs. 

Technical underpinnings: Fedora

Microsoft’s Linux 4.0 is based on Fedora Linux. As Lachlan Evenson, Microsoft’s principal program manager on Azure’s open-source team, told me, “We made a decision to use Fedora as an upstream, so it’s using RPMs in the Fedora ecosystem. Microsoft curates the packages and the supply chain to fit Azure’s cloud platform. Primarily, it’s purpose-built for Azure, which integrates vertically into all of our infrastructure to give you the best Azure Linux experience on Azure.” However, users can run it anywhere, just like any other Linux distribution. 

Azure Linux’s GitHub project outlines a build system that consumes Tom’s Obvious Minimal Language (TOML) configuration files to produce signed RPM repositories and multiple image formats. These include Virtual Hard Disk (VHDs) for Azure, container images, and bootable ISOs.

Azure Linux, which is still in beta, ships with a hardened Linux kernel 6.18. As you’d expect, it’s tuned for Hyper‑V and Azure VM performance. Azure Linux also comes with SELinux‑based security and a default configuration aimed at cloud and server workloads. It doesn’t include a GUI, so unless you’re like me and perfectly comfortable using the Bash shell as your interface, it’s not a desktop.

Also: Your Linux PC has a Secure Boot problem – what to do first (and the workaround to avoid)

You will soon be able to deploy Azure Linux for Windows Subsystem for Linux (WSL) on your developers’ workstations. This way, your developers can work with it without worrying about the constant headache of a manual developer-to-cloud workflow. 

Azure Linux includes the standard Linux server tools, such as SSH, as well as Azure agents and extensions for monitoring, diagnostics, and identity integration. While you could use it as a standalone server, at this early stage of its development, you’d still be better off with more fully featured Red Hat-based servers such as AlmaLinux and Rocky Linux. 

Azure Linux positioning

In the Azure Marketplace, Azure Linux 4.0 is described as a “Microsoft‑built Linux distribution for Azure.” Microsoft emphasizes a supported lifecycle, CVE patching, and integration with Azure security features, such as confidential computing and Defender for Cloud. If you want to use the distro on Azure, which, of course, Microsoft wants you to, it comes with formal support and Service Level Agreements (SLAs).

However, if you want to run the distro on your own hardware, you’re on your own. As its GitHub page spells out, “Support for the ISO is community-based,” and, specifically, “Bare metal, ISO images, on-premises, and other clouds aren’t supported.” Additionally, customized images are supported only when built on top of a prebuilt Azure Linux image (for example, with Image Customizer). Images built from scratch from the Azure Linux sources on GitHub aren’t covered.

Microsoft uses this dual positioning — ISO for standalone use, Marketplace image for the Azure cloud — to present Azure Linux 4.0 both as a conventional server OS and as part of its managed infrastructure stack.

Build system and openness

The Azure Linux GitHub repository exposes much of the distro’s machinery: package specs, build scripts, configuration files, and documentation for generating custom images. Microsoft also encourages contributions in the form of bug reports, issue discussions, and proposals. 

Also: After 30 years with Linux, I gave Windows 11 a chance – and found 9 clear problems

At the same time, Microsoft retains tight control over what lands in the base image, reflecting a curated, vendor‑controlled model rather than a community‑governed one. Which, let’s face it, isn’t in the least bit surprising. In all fairness, it’s also the same development model used by major enterprise Linux companies such as Canonical, Red Hat, and SUSE.

That said, by offering a free, Azure‑optimized server OS that can also run on‑prem, Microsoft hopes its customers will use Azure Linux as its single Linux operating system across hybrid environments. Ideally, for Microsoft, this approach will tighten the integration between Linux and its broader Azure stack. After all, for almost a decade, Linux, not Windows Server, has been Azure’s most popular server operating system. 

With the way things are going, I can see Microsoft eventually retiring Windows Server once and for all in favor of its own Linux server. You read it here first, folks.