[ekimekim]

To add to the sibling comments, after going from a jsonnet-based setup to a Typescript-based one (via pulumi), the biggest thing I missed from jsonnet was the native object merge operations which are very useful for this kind of work as it lets you say "I want one of these, but with these changes" even when the objects are highly nested, and you can specify whether to merge or override for each individual key.

But ultimately this was a minor issue and I think it's far more important that you use something like this (whether a DSL or a mainstream PL) and that you're not trying to do string templating of YAML.