set environment variable

Insert these lines of code to the config/application.rb after lineconfig.assets.version = '1.0':

config.before_configuration do

      env_file = File.join(Rails.root, 'config', 'paypal.yml')

      YAML.load(File.open(env_file)).each do |key, value|

        ENV[key.to_s] = value

      end if File.exists?(env_file)

    end