It's not the big acquisitions that are baffling; it's the little ones. What would a giant like Microsoft want with Deis, a relatively tiny outfit that's long offered a Heroku-esque PaaS?
Answer: Kubernetes. Google's container management system has become as vital to the container world as Docker. And Microsoft, fresh from adding Kubernetes support on Azure, is out to ensure its users don't have second thoughts about picking a fast-moving, fast-growing technology.
Most acquisitions are as much about the software team behind a product as they are about the product. In Deis's case, it's worth looking at its main software projects, aside from the Deis PaaS, to see what Microsoft is likely to gain by snapping them up,
Helm
The skinny: Described by Deis as a "package manager for Kubernetes," Helm packages, obtains, and installs applications that use Kubernetes as a foundation. In that sense, it's akin to Docker Hub or Quay, although with some more management functions sprinkled on top.
The benefit: Helm provides automation for assembling a Kubernetes-based application so that the app can be put together anywhere Kubernetes runs. It also provides useful tools, such as the ability to easily roll back an application to a previous version with a single command.
All this would be vastly useful to have in Azure as a complement to the existing Kubernetes offerings. It wouldn't only make it easier to compose Kubernetes apps in Azure, but to move existing Helm-composed apps there as well.
Workflow
The skinny: As the name implies, Workflow is a workflow system for apps built on Kubernetes, so code can be automatically built and deployed with a simple push. It also allows Heroku buildpacks to run as-is in a Kubernetes-based environment.
The benefit: If deployed natively on Azure, this would allow existing Heroku buildpacks to run without being reworked. It also theoretically provides a native workflow mechanism for Kubernetes apps on Azure that wasn't there before.
Steward
The skinny: This project is a Kubernetes-native service broker. Steward serves as a gateway between cluster applications and both internal and external services, making even external services available in ways that are consistent with Kubernetes' resource management primitives and abstractions.
The benefit: Given that this is an alpha-stage project, it's premature to expect anything built with it to be integrated with Azure soon. Assuming it meets its goals, the long-term benefits for Azure users should be noteworthy. Microsoft has been big on Azure for creating and consuming microservices, and Steward can help Kubernetes-powered apps fit that picture.
The Microsoft blog post announcing the acquisition acknowledges that Deis' work "gives developers the means to vastly improve application agility, efficiency and reliability through their Kubernetes container management technologies." It's also clear that the individual projects aren't going away or leaving the open source domain, so they can continue to be used as-is on one's own terms.
Still, Microsoft has plenty of options to stir these tools into its Kubernetes offerings -- and from the look of it, they're only the start for Deis bolstering Azure generally.