How to set the public-address of a unit upon deployment?

In an environment with MaaS (2.8.5) and Juju (2.8.10), how is it possible to control which public-address an application’s unit will be exposing? In my example, after juju deploy the unit’s public-address is always on the subnet on which PXE boot happens.

Note: --bind nor --constraints options seem to have any effect on the public-address.

Any help on that one?