Separate from any of those, a good chunk of America's more sensitive production database clusters, other workloads, and some network applications are scheduled by Nomad or Kubernetes running directly on a kernel that is not Linux.
The most popular kernel is not necessarily appropriate for all use cases or types of environments where high-value targets reside.
Directly downstream of FreeBSD, HardenedBSD achieved its long history of invulnerability to what were exploitable vulnerabilities in upstream through its advancements in the operating system layer.
https://hardenedbsd.org/content/easy-feature-comparison
_> but security thru obscurity
Arrogance is stupidity.
In some advanced settings where tolerances for potential impacts resulting from exploited software vulnerabilities are intensely low, Kubernetes (userspace software) on HardenedBSD is choice for mission.
Like with the other two systems, those running Kubernetes userspace on them are self-sufficient and are not among the audience of external more general Kubernetes distro support channels.
If you happen to like RKE, check out https://Talos.dev which is the best Kubernetes on Linux distro (for most Kubernetes on Linux use cases).
_
@nijave
Nomad and Kubernetes schedule containers, which are rarely not Linux containers, yeah.
Both can schedule processes in FreeBSD's BSD Jails.
If someone wants to start an open Kubernetes on FreeBSD/HardenedBSD project I would encourage that. Personally I would like to see an open Kubernetes on illumos project.
As far as I know where Kubernetes on HardenedBSD runs is not interested in open projects.
The other thing that was obvious earlier was that the OS mentioned previously was not Windows.
Maybe you're thinking of jails? I'm not sure if there's any mainstream/popular distributed orchestration systems for those.