Comment 6 for bug 1664806

If you are configuring a DNS server, you must have a route to that DNS server. The routing information should be part of the yaml: this would manifest as either a static route possibly the default route), or a declaration that the interface should be autoconfigured (dhcp). So MAAS should already have enough information to know which subset of interfaces to attach the DNS server settings to. Is there a reason not to construct the yaml this way?

This seems to map more correctly to the underlying primitives on networkd and network-manager, and I think we should only change the yaml definition if we think we need to support something that can't be represented this way. An example I could think of would be that you want to express "auto-configure this interface with dhcp, which should give you a default route; and may give you dns servers; but just in case it doesn't, here are some fallback servers that you should list with lower priority." That could be a reason to define top-level dns servers that are then fed into resolved directly, rather than to networkd / network-manager. But I doubt this is the use case MAAS cares about?