Here's a stab at documentation.
Denominator aims to allow common functionality across DNS providers.
New cloud providers are encouraged, provided they are supportable.
Prerequisites
Before starting work on a cloud provider, make sure it has a user who
isn't the vendor. All code needs to have clear purpose, and
non-authors with "skin in the game".
Moreover, we will not accept cloud provider code unless someone who
isn't an author is given credentials and a test endpoint. If a cloud
provider isn't live tested in 3 months in an active denominator
release, it will be deleted. The best way to facilitate enduring
support is to engage an official DNS provider support channel with
your efforts towards denominator support.
https://github.com/Netflix/denominator/wiki/Adding-new-Providers