So I think we may be able to follow the convention set using `rails_config` gem.

See: https://github.com/sul-dlss/SearchWorks/blob/master/config/settings/test.yml

If you configure the url eg (STACKS_URL: "http://xyz.com") for each file (config/settings/[test,production, development].yml) it should be available as `Settings.STACKS_URL`