OpenStack is an open-source cloud framework backed by Red Hat (RHT) , Rackspace (RAX), Hewlett-Packard (HPQ), Cisco (CSCO) and others as the basis of their own cloud efforts. And Mirantis, which started out as a specialist in tying together and testing various OpenStack components from many vendors but then decided to offer its own version, is working with most of those companies. In fact, it has already worked with Oracle to make sure OpenStack runs well with Oracle’s version of the Linux operating system and virtualization technology.

But the database remains the central key to the Oracle (ORCL) kingdom. It is used by most Fortune 500 companies, actually by most big companies, period, so this pact is a statement that Oracle now sees OpenStack as a key piece of infrastructure.

This new deal focuses on the latest Oracle 12c “multitenant” database, available since last summer, which enables companies to pack a bunch of database workloads onto a single machine, like Oracle’s Exadata server for workload consolidation.

Mirantis co-founder and chief marketing officer Boris Renski acknowledges that you could always take an Oracle database and put it in a virtual machine to be managed by OpenStack. But databases are core, mission-critical applications and are typically “owned” and managed by a select, and separate group of administrators in a given company.

“This deal means that companies can integrate with that core piece of technology much more easily and access it via OpenStack,” Renski explains.

The upshot of this deal is that Oracle 12c will run on Oracle and Mirantis OpenStack distributions in a fully-supported way, although one selling point of the OpenStack Foundation is that an application that runs on one version of the cloud should run on all versions. This interoperability story will be a big focus at next week’s summit.

Oracle was late to OpenStack, joining the OpenStack Foundation a year ago, well after rivals IBM (IBM) and HP were fully aboard, but it appears to be making up for lost time. Last week the company hired a phalanx of OpenStack talent out of now-defunct Nebula.

When it launched out of NASA nearly five years ago, OpenStack was seen as a way vendors could build their own private clouds (which run a customer’s applications on their own, private gear) or public clouds (which combines many customer workloads on shared infrastructure). Almost every tech vendor with the exception of Microsoft (MSFT), Amazon (AMZN) and Google (GOOG) are part of the foundation.