title: Custom rails config for every domain
body: <p>I have an option, which should be set only for users who enters rails application via "domain.com" domain</p>
  
  <pre><code>config.session_store :cookie_store, :key =&gt; '_builder_session', 
  :domain =&gt; 'domain.com'
  </code></pre>
  
  <p>How to write a condition?</p>
  
  <p>I have tried <code>if request.domain == 'domain.com')</code>, but <code>request</code> is not defined in <code>/config/environments/development.rb</code> yet</p>