That's nice. seems to be the infrastructure required for building such system. question is how do you come about building the manifests? Users need to do that???
In practice, most of the work happens in the base image. Future versions simply extend the manifest with a few extra lines.
Ideally you want to "compile down" to cloudlets. With smart change management tools you can make it really simple for the user. That sounds exactly like Stackrocket's cup of tea :)