added flag to control app subdomain option

app/controllers/data_app_controller.rb

@@ -19,16 +19,14 @@ class DataAppController < ApplicationController
 
   def _app_auth_url
     # apps require a proxy server (like nginx)
-    return nil unless (
-          request.headers.key?("HTTP_X_APP_BASE_URI") or
-          request.headers.key?("HTTP_X_APP_SERVER_NAME"))
+    return nil unless
+          request.headers.key?("HTTP_X_SUBDOMAIN_APPS")
 
-          # try to use the server name header, otherwise try the base_uri
     token = InterfaceAuthToken.create(data_app: @app,
                                       user: current_user,
                                       expiration: 5.minutes.from_now)
     # proxy supports subdomains (preferred because more secure and flexible)
-    if request.headers.key?("HTTP_X_APP_SERVER_NAME")
+    if request.headers["HTTP_X_SUBDOMAIN_APPS"] == 'true'
       server = request.headers["HTTP_X_APP_SERVER_NAME"]
       scheme = request.headers["HTTP_X_APP_SERVER_SCHEME"]
       "#{scheme}://#{token.data_app.id}.app.#{server}?auth_token=#{token.value}"