development:
  some_service:
    host: localhost

production:
  some_service:
    host: some_service.production.com

flexible:
  foo: <%= ENV['FOO'] %>
  var_with_default_not_in_env: <%= ENV['SOME_VAR_NOT_IN_ENV'] || 'default_value' %>
  var_with_default_in_env: <%= ENV['FOO'] || 'default_value' %>