The new deployment API (#1743) specifies some out of the box strategies (recreate, rolling) which will be implemented inside the deployment controller. It's possible these strategies may not cover all deployment needs for end users, or for downstream users (such as OpenShift). The deployment system should enable:

1. Users to define their own deployment strategy logic in a custom Docker image.
2. Downstream systems to define deployment strategies in a delegate controller.

It's possible these two capabilities are related but orthogonal in their design/implementation. I'm starting the discussion here so we can collect initial thoughts and start linking any existing relevant issues.