Sure, we can all improve but I just want to note one thing. The "Silly" config that MAAS sends to curtin is valid config. That yields valid configuration in Xenial. Since Curtin is now passing the /same/ configuration to cloud-init, cloud-init is not generating valid configuration in Bionic. Despite the fact that theres a "global" DNS, there's also DNS defined for the bridge, but cloud-init is not writing the bridge config correctly.
@Scott,
Sure, we can all improve but I just want to note one thing. The "Silly" config that MAAS sends to curtin is valid config. That yields valid configuration in Xenial. Since Curtin is now passing the /same/ configuration to cloud-init, cloud-init is not generating valid configuration in Bionic. Despite the fact that theres a "global" DNS, there's also DNS defined for the bridge, but cloud-init is not writing the bridge config correctly.