title: override omniauth github callback uri
body: <p>I recently deployed a couple of rails app servers behind elastic load balancer using the wizard in elastic beanstalk. I set up SSL and tested to ensure the app routes return data, they do, and the green checkmark shows up showing SSL is installed. Sweet!</p>
  
  <p>I have been previously using single app servers. Unfortunately, now that I have several behind elastic load balancer, it seems like i have broken my github oauth integration via omniauth. The error I'm getting is a redirect uri mismatch. The github app is set up to call back to <a href="https://my-load-balancer.com" rel="nofollow">https://my-load-balancer.com</a>, but the oauth request being sent to github:</p>
  
  <p>GET /login/oauth/authorize?</p>
  
  <p>has a param redirect_uri which is filled out automatically by omniauth with <a href="https://my-app-server-number-one.com/callback-slug-here" rel="nofollow">https://my-app-server-number-one.com/callback-slug-here</a>. This is a mismatch to the load balancer address. Github's documentation suggests to remove the redirect_uri parameter from the request, and it will automatically send to the registered callback URI instead of the currently erroneous uri in the query string.</p>
  
  <p>I checked the omniauth and omniauth-github docs but wasn't able to find a great explanation of configuration. is it possible to override this parameter?</p>
  
  <p>Thanks!</p>