From https://once.com/writebook

app/channels/application_cable/connection.rb

@@ -0,0 +1,20 @@
+module ApplicationCable
+  class Connection < ActionCable::Connection::Base
+    include Authentication::SessionLookup
+
+    identified_by :current_user
+
+    def connect
+      self.current_user = find_verified_user
+    end
+
+    private
+      def find_verified_user
+        if verified_session = find_session_by_cookie
+          verified_session.user
+        else
+          reject_unauthorized_connection
+        end
+      end
+  end
+end