How open is the OpenStack cloud computing distribution that VMware (VMW) recently launched? Not very, according to OpenStack vendor Mirantis, which is loudly touting its own ability to integrate its “pure-play” OpenStack distribution with VMware infrastructure while keeping the cloud open.

Mirantis promotes its OpenStack distribution as “the most open, flexible distro, built for zero lock-in.” And it is eagerly using that characteristic as a basis for responding to VMware’s decision to launch a new OpenStack distribution tightly bound to the VMware software stack.

In a statement sent to The VAR Guy, Mirantis CEO Adrian Lionel commented as follows on the VMware news: “VMware has made big contributions to OpenStack and today’s announcement recognizes that OpenStack is gaining huge traction in its customer base.” But he continued, “While WMware now offers improved integration with OpenStack, it does not offer a full and open distribution. That’s why Mirantis OpenStack remains the top choice for OpenStack amongst VMware customers and we have a partnership in place to support the integration of our distro with VMware technologies.”

Mirantis representatives have also questioned the significance or accuracy of VMware’s claims in announcing its OpenStack distribution that the company has  “30 developers dedicated to writing OpenStack code” and “we are the fourth-largest software contributor to OpenStack.” Mirantis has “hundreds” of developers committed to OpenStack work, it says, and points out that according to Stackalytics, VMware is far from the top of the list of major OpenStack contributors.

This all said, tensions between Mirantis and VMware should be viewed within the context of the two companies’ complementary needs. VMware is eager to get in the OpenStack game, to which it has arrived late and without any of the deep specialization in OpenStack that Mirantis can boast. Mirantis, meanwhile, needs its OpenStack solution to appeal to VMware customers if it wants to keep expanding. So at the end of the day, the two companies may end up needing one another in ways that aren’t obvious from the VMware news and Mirantis’s reaction last week. Something tells The VAR Guy that this is a story worth continuing to watch.