Juju can use MAAS as a Cloud to provision resources. We can select which machines in MAAS will be used by using constraints, that can range from selecting a machine by its tag, available resources or even creating a new virtual machine from a KVM host with the desired resources.
If the zone has a KVM host, we can add a new virtual machine specifying the desired resources:
juju add-machine --constraints="virt-type=virtual-machine cores=2 mem=4G root-disk=30G zones=az1" --base ubuntu@24.04A really weird behavior is that, even with the virt-type=virtual-machine, if the zone does not have a KVM host Juju will ask for any machine in MAAS that has the minimum resources in the AZ, so you can end up commissioning a physical host by accident.
When dealing with a small number of physical machines, I prefer to tag them in MAAS and then use the tags constraint.
juju add-machine --constraints="tags=node1" --base ubuntu@24.04