nginx snippet showing how to configure transparent backend proxying

snippet

  #
  # This is the proxy location  which is used when try_files
  # can't locate a static file to send the requester
  #
  location @unicorn_server {
  
    #
    # Pass requests for this location to
    # the upstream named `unicorn_server`
    #
    proxy_pass http://unicorn_server;
    
    # Allows the back-end to see the original request
    # important if you use request.<methods> in your app
    proxy_set_header Host $host;
    
    # This ensures that when a down-stream proxy error
    # is raised that nginx handles it using the error
    # handling we have configured in this file
    proxy_intercept_errors on;

  }