There are more than 331,000 organizations with employees contributing to open source projects on GitHub, a sign that open source software is eating the world. But in a sign that open source is sending that same world into an early apocalypse, the biggest corporate contributor to open source is Microsoft, according to new GitHub data.

Huh?

Microsoft, which used to deploy catchy marketing slogans like "Linux is a cancer" and "open source is un-American," didn't morph overnight into a cute and cuddly open-source-loving contributor. Rather, the Microsoft that fought open source as an existential threat to its business simply learned to do business in a new, cloudy manner.

In this new services-based revenue model, open source is Microsoft's best friend.

Redmond gives the most

Microsoft's initial foray into open source was hardly promising. Recognizing a threat to its Windows business, Microsoft took a passive-aggressive approach to open source. On the passive side, the company actively sponsored open source events. In fact, the first sponsor of my Open Source Business Conference in 2004 was Microsoft at the Platinum level (quickly matched by IBM).

On the aggressive side, few could be as surly about the alleged risks of open source than Microsoft. Initially led by Martin Taylor, Microsoft's anti-open-source efforts took the form of one-sided "studies" that somehow always found open source projects lacking and Microsoft products unparalleled, marketing campaigns that urged enterprises to "get the facts," and funding patent royalty shakedowns to discourage adoption of Linux.

Today, Microsoft sings a different tune.

According to GitHub's latest data, Microsoft has surpassed open source stalwarts like Facebook and Google to become the world's top open source contributor with 16,419 contributors. Facebook, by contrast, employs 15,682, while Google has 12,140. Red Hat, the company most often touted as the world's largest open source company, doesn't even make the top 10.

The key to Microsoft's change of heart is actually nothing of the sort. It's a change of business plan.

The cloud likes open source

Sure, let's give credit to Microsoft CEO Satya Nadella for changing the tenor of Microsoft's culture. But if we look to the roots of Microsoft's altering affection for open source, that actually started under Steve Ballmer, not Nadella.

It was Ballmer, after all, who hired Jean Paoli to run Microsoft Open Technologies. It was Ballmer who kick-started the open-sourcing of .Net and welcomed the introduction of Microsoft's code repository, CodePlex. And it was Ballmer who served as the early shepherd of the thing that today makes open source not merely possible, but probable, at Microsoft: Azure.

Microsoft Azure, the cloud platform that competes with Amazon Web Services, has changed the way Microsoft thinks about software. So has Office 365, the Xbox, and a range of other Microsoft products that are delivered as or depend upon software services, rather than software licensing. Though Microsoft continues to print billions of dollars in profit from its legacy licensing business, it's the cloud that fundamentally defines Microsoft's future, as well as its relatively recent love for open source.

I've gone on the record as declaring there's no money in open source, and I stick to that. But there's plenty of cash in the cloud, and for a platform company like Microsoft, the value of its cloud business is directly tied to a mighty bear hug embrace of open source on that platform. As I've written, "The companies that make the most money from open source software don't sell it: ... Google, Facebook, and other giants ... heartily embrace open source without having to sell a single line of it ... [because] they sell services based on open source."

Microsoft increasingly sells services built on top of open source projects like Apache Spark, but the company also makes Azure a welcome home for others' open-source-based software applications. As such, we should expect pigs to keep flying and Microsoft to keep loving open source. It's a self-interest thing.