[model, enhacement] VM's inside a MAAS deployed KVM host (pod) should be modeled as a node with a parent

[Andres Rodriguez]

I'm filing this bug to start a discussion about this.

Users can register "devices with a parent" to represent containers or VM's that are created inside a machine in MAAS. These are usually listed in the 'containers' tab inside a machine listing page.

When we create a pod on a MAAS deployed machine, these are effectively virtual machines with a parent, because they live inside the machine that was deployed by MAAS and it would be nice to have this represented the same way.

The only caveat is that currently, "devices with a parent" are not really machines that MAAS can manage, but VM's inside a KVM host are.

The other option would be to add a 'Virtual Machine' tab in the machine listing page, but they should still be modeled as "machines with a parent".

[Mike Pontillo (mpontillo)]

Yes, it would be nice to have this better represented in MAAS. I feel it's a risky change for this late in the 2.5 cycle.

You can currently view the machines in a pod on the pod details page, so I don't think it's critical to get this into 2.5.

There is also an edge case we should consider: it's possible to move VMs between different instances of libvirt. Refreshing a pod would need to update MAAS's idea of which VMs are children of which deployed node.

I also feel that we shouldn't hide VMs behind their parents such that they just disappear from the machine listing and can't be found anywhere. They should either still show up as machines that can be managed like any other MAAS machine. I agree that a "Virtual Machines" tab might be appropriate, as an alternative.