A presales field note about a customer who wanted Docker on a Windows Server VM — on a platform with no nested virtualization — the two traps I hit proving it works, and the one check that made the whole question disappear.

The request came in short and sure of itself.

"We need Docker on our Windows server. Our developers ship containers."

The server was a Windows Server VM on a KVM-based hyperconverged platform. Nested virtualization was not enabled on it.

"Which Docker? Docker Desktop?"

"Yes. That's what the developers use."

I asked one more question.

"Are the containers Windows containers or Linux containers?"

A pause.

"They're just containers."

That's the trap. "Docker on Windows" sounds like one thing. It is at least three different things, and on a VM without nested virtualization, two of them cannot start at all.

What Nested Virtualization Has to Do With Docker

Nested virtualization is a hypervisor letting a VM run its own hypervisor inside it.…