It's happened at last: Microsoft has its own version of Linux. But don't expect to download an .ISO just yet. It isn't publicly available -- it's an internal project developed to help run Microsoft networks such as Azure.
Microsoft's Azure Cloud Switch (ACS) is not a Linux distribution on the order of Red Hat's or Ubuntu's; rather it's closer to Cumulus Linux. ACS was built specifically for Microsoft's own needs, and therefore is not a definitive sign that Microsoft is becoming a Linux player.
All in the Microsoft family
As described in a blog post yesterday, ACS is "a cross-platform modular operating system for data center networking built on Linux." It is intended to run on commodity ASIC hardware from multiple switch vendors and to run Microsoft's own software for managing network devices.
While it was built with Linux and uses the Switch Abstraction Interface (SAI) specification developed under the Open Compute Project, Microsoft states that ACS was designed to integrate with Microsoft's monitoring and diagnostics systems.
This integration "[deviates] from the traditional enterprise interactive model of command line interfaces...[but] allows for switches to be managed just as servers are with weekly software rollouts and roll backs thus ensuring a mature configuration and deployment model," the blog says.
This also is similar to Cumulus Linux, which is devised to run switches as simply another piece of software (and hardware) to be managed with conventional enterprise tools. In Cumulus' case, the management tools are software like Puppet or Chef; in Microsoft's case, it's Microsoft's system-management technology.
For their eyes only
What will Microsoft likely do with ACS in the long term? One possibility: ACS will be offered to users as a way to build a more Azure-like environment within their data centers -- much as Microsoft is planning to do with Azure Service Fabric.
The competitive edge Azure provides for Microsoft in the cloud is bound up with the likes of ACS. Still, every cloud has to keep innovating; in time, Microsoft may offer ACS freely, but probably only after the advantage it provides Azure has been superseded by other, more ambitious features.
If ACS becomes the closest thing to a Microsoft-branded Linux distribution, it will -- like all the other work the company has done with Linux -- be a way to better support Microsoft's proprietary cloud efforts. Linux users will win out by having better support in Azure for their OS of choice. But Microsoft's first duty, as always, is to Microsoft itself.