You might ask why I've written this gem. And indeed you would be right to question this! The main reason is error handling. If you use the high level interface in the official ruby client and you make a mistake in a query then you get a big fat nothing. Yup, nowt. This isn't that different from the official gem but I've used a number of dry-rb libraries to generally improve the code and specifically to improve the error handling.
This isn't on Rubgems yet so you'll have to add it
to your Gemfile as a git repo:
gem "prometheus-api", "0.3", :git => "https://github.com/filterfish/prometheus-api"