According to a talk earlier this year at the Linux Foundation Open Source Summit by Microsoft Azure Linux Platforms Group programme manager Jack Aboutboul, Linux is the #1 operating system in Azure today.

And all must be supported in a way that Microsoft users have come to expect. Hence, Microsoft's Linux Platforms Group is needed to provide Linux support to internal and Azure customers. These days, Vole Microsoft knows as much as anyone about operating Linux on a hyperscale.

He said hundreds of Azure and Azure-based services are running on Linux, including the Azure Kubernetes Service (AKS), OpenAI, HDInsight, and many other database services.

"A lot of the infrastructure powering everything else is running on Linux. They're different flavours of Linux running everywhere," Aboutoul said.

To run these services, Microsoft maintains its kernel, Azure Linux, and in 2023 the company released its version of Linux, Azure Linux. However, Azure Linux is just a tiny portion of all the other flavors of Linux running on Azure, all of which Microsoft must work with to support it.

About 20,000 third-party Software as a Service (SaaS) packages in the Azure marketplace rely on some Linux distribution. When things go wrong, Azure service engineers get help tickets. The company keeps a set of endorsed Linux distributions, which include Red Hat Enterprise Linux, Debian, Flatcar, Suse, Canonical, Oracle Linux, and CentOS (as managed by OpenLogic, not Red Hat).