Microsoft just buried the hatchet with another huge and bitter rival, Red Hat

Microsoft and Red Hat struck up a major new partnership on Wednesday. They're giving Red Hat's Linux operating system a starring role on Microsoft's cloud computing service, Azure.

Linux is a free and open source competitor to Windows offered by a number of players, with Red Hat being the biggest.

Microsoft has had Linux computer servers on Azure for a couple of years now but Azure never supported Microsoft's arch rival Red Hat. Microsoft was instead offering versions that compete with Red Hat like OpenSuse, Canonical Ubuntu, and CentOS, a free open source knockoff of Red Hat.

Microsoft says that 20% of the servers it rents on Azure run Linux these days. As Microsoft's cloud becomes more successful, Red Hat was being cut out of that business. At the same time, Azure customers want to use the most popular version of Linux, which is Red Hat's software.

So, if Microsoft really "loves Linux," as it loves to say it does these days, it was high time for this partnership.

Still the fact that it actually happened shows just how warm and fuzzy Microsoft has come under CEO Satya Nadella.

More than a decade ago, Microsoft's then-CEO Steve Ballmer declared war on the Linux operating system, with Microsoft insisting that Linux violates a bunch of its patents. (Since then, and to this day, it's been using that claim to get Linux and Android device makers to sign patent licensing deals with Microsoft, turning its patent licensing operations into a decent business.)

The anti-Linux thing at Microsoft has long since run its course and is fairly well dead under Nadella as well as Scott Guthrie, the Microsoft exec running Azure.

And so another one of Microsoft's long-standing, often hostile rivalries has come to an end. Microsoft has already made nice with Salesforce and many others.