The initial goal was to write a command-line utility that aided the deployment of various IaC organised in a particular file structure. As I designed the solution, it became clear that a general approach to running commands against globs of files using a recursive structure would be extremely beneficial to more than just deploying IaC.
This open-source tool is written in Haskell and continues to receive development. It has two complementary features; a JSON / YAML data merge and file templating using Mustache syntax. These features are all rolled into the final process command or accessed separately.