Juju does the same thing with MAAS 1.8 and 1.9 for containers - creates a device with a known (juju-generated) MAC address and claims a sticky IP for it, linking the device to the container's host node. Cleaning up the leases for the containers is then up to MAAS - when the device representing the container is removed, along with its parent.
So if that does happen on 1.9, but not on 1.8 then it's obviously a MAAS 1.8 issue, fixed in 1.9.
Juju does the same thing with MAAS 1.8 and 1.9 for containers - creates a device with a known (juju-generated) MAC address and claims a sticky IP for it, linking the device to the container's host node. Cleaning up the leases for the containers is then up to MAAS - when the device representing the container is removed, along with its parent.
So if that does happen on 1.9, but not on 1.8 then it's obviously a MAAS 1.8 issue, fixed in 1.9.