Ah right, guess I was thinking of the protobuf over HTTP API. In any case, I find using the protobuf types in your language of choice pretty ergonomic compared to YAML.
This is one thing that mesos/aurora got right (the "turing-complete-by-design" config files, written in Python). Templating yaml is like templating html. It works but absolutely sucks at scale if your job is to maintain it.
It's good to know that such an interface could conceivably be built for Kubernetes, using the HTTP API. Even better that it supports any programming language (since it's a network interface); I'd see that as a step-up from aurora configs, in fact.
At some point, I imagine this will become the default way that Smart Organizations build around k8s, once k8s's core API is super-stable and people develop sound frameworks in $POPULAR_LANGUAGE for declaring your configuration.
Then, we can then banish yaml to the same fate as json and xml. One can dream, at least. :)
I don't have an example offhand, but mentioned skycfg in the neighbor comment, which may be of some interest to you. I've used
https://github.com/ericchiang/k8s in the past with great success.