The group touts Kubernetes, a hot technology used to deploy and manage what are known as software containers. Containers let businesses pack the components needed to run a given software application into bundles that can theoretically run in their own data centers or an outside public cloud. In that way it helps the customer avoid being locked into any one cloud provider.

Microsoft’s membership in the group is a formal endorsement of Kubernetes.

Using applications that can be operated on-premises or off is attractive to Fortune 500 companies. They can put their software where it runs best and then more easily move if another, better venue becomes available. Cloud companies trade price cuts and new types of computing all the time. Being able to move IT to the better/cheaper provider is a big deal.

Microsoft (MSFT) joining the CNCF is also interesting because it leaves Amazon (AMZN), the largest player in the booming public cloud market, as the only major cloud computing player not in the group. Oracle, a smaller player in the industry, is also MIA from the foundation.

Amazon introduced the public cloud model in which customer applications run in its data centers more than a decade ago. In the years since, many players including Alibaba (BABA), Google, Microsoft, IBM (IBM) have jumped into the market.

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The Kubernetes technology pushed by the foundation originated at Google (GOOGL), which competes with both Microsoft (MSFT) and Amazon Web Services (AWS) in the cloud. Two years ago Google turned the project over to the foundation.

With Microsoft joining, the group could be seen as an “Anyone But Amazon” gang that also includes Google, Alibaba, Cisco (CSCO), Dell Technologies, AT&T, Fujitsu, Huawei, Supernap, Joyent, and Docker.

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Instead of Kubernetes, AWS fields its own rival Elastic Container Service (ECS) to run containers on its own infrastructure. But ECS runs only on AWS, so it doesn’t offer the same portability story as Kubernetes, which runs on many clouds or on premises. Then again, given the massive size of AWS and its customer base, that may not matter.

Some think Amazon’s anti-Kubernetes stance is softening. Last week, tech news site The Information reported that Amazon is exploring its own Kubernetes-based container management system. AWS could not be reached for comment.

But some aren’t buying that. As Constellation Research analyst Holger Mueller put it: Market leaders can set their own agenda. He does not expect Amazon to budge change its take on Kubernetes.