title: What is the difference between a Cookie and Redis Session store?
body: <p>I want to share sessions among 2 applications on different nodes; however, I am confused what the difference is between Cookie and Redis session stores; e.g. a cookie session might look like this:</p>
  
  <pre><code>rack.session=BAh7BkkiD3Nlc3Npb25faWQGOgZFRiJFN2YxZDMxMGE5YTNhZjc2NGM1NDBk%0AMzdiODQ0MjcyMzk5MzAxY2YyYzdhNDMwOWVkMzhiNWVlMmY2N2QwYzExNg%3D%3D%0A--ec4ec7b5a807c806e02e2811f4a11d05877a7698
  </code></pre>
  
  <p>In Redis, a session-store, might look like this:</p>
  
  <pre><code>rack:session:eb23c0a055e9e6de3b8ad51efd9g6260d647b2e61326e35f5ff59cd490bfb405"
  </code></pre>
  
  <p>However, I am confused how these sessions can be shared. Whereas in a cookie approach, a request carries the state of the session, I can't see how the session in Redis actually matches to state among 2 applications. Any advice how to use Redis / share session state among 2 rack apps?</p>