We are using the databricks terraform provider to handle... everything really. Then we use a CI runner (in our case azure pipelines) to deploy to dev/test/prod depending on branches and stuff in git (you might prefer tags/branches whatever your branching strategy is).

It works pretty good, EXCEPT, validating mounts take a long time (10-15 min) because it needs to spin up a cluster. That is pretty lame, and the only fix seems to be for databricks to make a REST API letting you list/modify mounts, but this is nowhere on any list.