One feature that I wish was supported in RDS is to migrate from a MySQL engine to Aurora engine without having to create new database instance at all. It looks like Amazon DMS makes this process easier, but since Aurora is fully compatible with MySQL, I don't see why I have to create a new database instance and point my application to talk to the new server when Amazon DMS could do this behind the scenes on the one I already have.
Or am I allowed to set the source and target databases to be the one and the same?
Not quite the same, unless I'm misunderstanding. I'm talking about an online migration on a single RDS instance with an engine switch handled fully behind the scenes. The link provided doesn't seem to handle data changes since the snapshot, and also requires a switch in the application to point to the new instance which has been restored via snapshot.
DMS gets closer than the above link, I think, since it will handle replication onto the target database for you. But, for two fully compatible database engines, it seems like you should be able to make the switch without having to fuss with replication configuration or spinning up a new instance at all.
Or am I allowed to set the source and target databases to be the one and the same?