MAAS prevents adding a VLAN to an interface that is already configured in a bridge

[David Torrey]

In MAAS 3.4, once an interface has been configured into a bridge, it is not possible to add a new VLAN to the interface without first removing that bridge. Consider the following fabric:

labnet: bond0 base interface with tagged VLANs 2, 3, and 4

In MAAS, I create the VLANs on bond0, yielding new interfaces bond0.{2,3,4}, and then create a bridges on the base interface and each VLAN, named br-base and br-net{2,3,4}.

If I then wish to add VLAN 5, I must first remove the br-base bridge before I am able to select the bond0 interface again to create a new VLAN.

This may be a matter of (best) practice, in that using the untagged base interface itself in a bridge has some odd side effects. For example, that bridge will contain *all* traffic on the base interface, including the other VLANs.

However, this is a legitimate configuration that the MAAS UI ought to allow. The UI should allow adding a VLAN to any appropriate interface, regardless of whether or not that interface is already a member of a bridge.