Microsoft Build 2026 was not Steve "Linux is a cancer" Ballmer's Build. Instead, Microsoft announced the arrival of Azure Linux 4.0, a general-purpose Linux server, Azure Container Linux, Windows 11 customized for developers that incorporates Windows Subsystem for Linux (WSL), and Surface RTX Spark Dev Box, a high-end AI workstation that comes preconfigured with WSL 2, native GPU passthrough, and full Nvidia CUDA support.

Also: Microsoft surprises with its first server Linux distribution: Azure Linux 4.0

Why? Besides the demand for Linux on the server and cloud -- today Linux is the most popular operating system on Azure -- AI development runs on Linux. There are no competitors. It's that simple. If you want to program AI, you're doing it on Linux. Period.

Azure Linux 4.0 is a Fedora Linux-derived, RPM-based, general-purpose server distribution for Azure virtual machines (VMs). This is Microsoft's first Linux server. Earlier versions of Azure Linux were designed to serve as dedicated Azure Kubernetes Service (AKS) container hosts.

With this version, Microsoft positioned Azure Linux as a hardened baseline for cloud-native and AI workloads rather than just Kubernetes underpinnings. Microsoft says the distro is built and maintained in-house, with a trimmed package set and an emphasis on supply-chain transparency.

Alongside that, Azure Container Linux, built on the Flatcar Container Linux lineage, is now generally available. Microsoft is pitching this immutable, container-optimized OS as its answer to Google's Container-Optimized OS and Fedora CoreOS. Interestingly, CoreOS and Microsoft's new container Linux spring from the same roots: CoreOS Linux. Microsoft's version gives you a locked-down host image for Kubernetes on Azure.