It's scary to think how many times I've had to evolve configuration options as systems developed and the user-base changed. As you say, I'd start out with INI

It's scary to think how many times I've had to evolve configuration options as systems developed and the user-base changed. As you say, I'd start out with INI files, then move on to JSON, after that it would come a hack to allow the JSON to be generated by executing a shell/ruby/perl script. (i.e. "--config=!xx" would execute XX and parse the output, instead of reading a file). Later still we started embedding lua, or similar, to allow things to be templated and "dynamic" on a per-host basis. I was always fond of the Apache-style configuration system, and I guess HCL is close to that, but there aren't any great universal solutions unless you go all-in with scripting, and then you end up with emacs!