When OpenStack launched out of NASA and Rackspace in 2010, it was pushed as a flexible way for businesses to run their data centers. Not coincidentally, it was also positioned explicitly as a hedge against having to rely on VMware software in their own server rooms and Amazon Web Services in the public cloud.
So, if you were an IT professional wanting a good way to configure servers, networking, and storage, OpenStack would facilitate that. The actual software was open-source, and thus free, or you could purchase supported versions from many vendors. That meant if one provider didn't meet your needs, you could move on.
All of this was an attractive proposition for companies sick of paying high VMware (vmw) license fees for virtualization software or worried that putting their IT into AWS meant too much reliance on a single vendor.
Seven years later things have shifted. The promise of IT flexibility is still there, but OpenStack's traction has been with large telephone companies, a smattering of what most would call second-tier public cloud providers, and inside corporate data centers, where it sometimes runs as a VMware-compatible technology. It is really not seen as an alternative to AWS or even VMware, which joined the OpenStack Foundation in 2012.
"The overall macro picture is that cloud computing has come a long way and looks a lot different than it did seven years ago," Mark Collier, chief operating officer of the OpenStack Foundation tells Fortune. "We had no idea it would be used by telcos like AT&T to route millions of calls."
But OpenStack has been slammed because its many components were seen as too complex for mere mortals to assemble. While the software could be had for nothing, the experience needed to make it work could be expensive. It didn't help that there were so very many vendors in the mix. OpenStack suffered from "too many cooks in the kitchen" syndrome.
OpenStack "was supposed to be like the Linux operating system for data centers, to replace VMware, and let companies build their own AWS-like cloud," says Randy Bias, who founded Cloudscaling, an early OpenStack company. It's pretty clear that didn't happen, and instead, OpenStack is found on private and managed cloud deployments, explains Bias, who is now vice president and technology strategist for Juniper Networks (jnpr).
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The public clouds running OpenStack are nowhere near as big as Amazon (amzn) Web Services, the leader in this market, which it rents out its own servers, storage, and networking to many companies. In the past year, other companies offering OpenStack-based public cloud—like Cisco and Hewlett-Packard Enterprise (hpe)—have backed off those efforts.
Nevertheless, OpenStack Foundation executives maintain that the technology remains relevant in public cloud.
"Just like in all markets, the OpenStack public cloud has seen companies enter and exit," Jonathan Bryce, executive director of the OpenStack Foundation, tells Fortune. "But the number of public clouds and data centers running OpenStack is bigger than ever."
Lauren Sell, the foundation's vice president of marketing and community services, says OpenStack public cloud providers include UKCloud—which she declared to be the fastest-growing public cloud in the U.K.—as well as OVH, a French service provider, Vexxhost in Canada, and Internap (inap) in the United States.
Forrester Research (forr) senior analyst Paul Miller says OpenStack's strength lies in its ability to run both in a public cloud and in a company's internal data centers. That's compelling for businesses that want to mix and match workloads in what is known as a hybrid cloud model.
As Sell put it, for most companies, the discussion is not private or public cloud—but private cloud and public cloud. "It's always 'and,' not 'or,'" she notes.
That does appear to be the case and hybrid is one area where public cloud giants AWS and Google lag, Miller says. That's why Google is backing Kubernetes, technology that promises to run software in any cloud or data center and Amazon inked partnerships with VMware and others.
Microsoft (msft), has also talked up hybrid cloud a lot, but has yet to ship Azure Stack—which will let companies run the the Azure software powering Microsoft's public cloud—in their own data centers.
So for now, it does appear that OpenStack is one of the few technologies that does span hybrid and public cloud models.