Rails Configuration Howto

application.rb

moduleConfigurator
  classApplication < Rails::Application
    # By default, let OSX resolve the path to the binary
    config.wkhtmltopdf = "wkhtmltopdf"
  end
end

environment.rb

## Use the appropriate environment file

Configurator::Application.configure do
  # Settings specified here will take precedence over those in config/application.rb
 
  # Point Heroku explicitly to the binary we need to use
  config.wkhtmltopdf = "#{Rails.root}/bin/wkhtmltopdf"
end

file.rb

cmd = [Configurator::Application.config.wkhtmltopdf, url, tmpfile.path]