The machine drivers contains VirualBox but no KVM/QEMU. Does it mean that
- virtual machines created by KVM/QEMU can't be used as nodes in Docker's swarm?
- Docker works with VirtualBox but not with KVM/QEMU? (If yes, it is surprising to me, since both Docker and KVM are supported by Linux kernel natively, while VirtualBox seems less so. Is Docker a reason to use VirtualBox instead of KVM/QEMU?)
If Docker can create virtual machines with KVM/QEMU type, then what is to be specified to