Handle empty scopes and always send the WWW-Authenticate header, as per spec

Fixes #1045

endpoints/v2/__init__.py

@@ -9,16 +9,13 @@ import features
 from app import metric_queue
 from endpoints.decorators import anon_protect, anon_allowed
 from endpoints.v2.errors import V2RegistryException
-from auth.jwt_auth import process_jwt_auth
 from auth.auth_context import get_grant_context
 from auth.permissions import (ReadRepositoryPermission, ModifyRepositoryPermission,
                               AdministerRepositoryPermission)
 from data import model
 from util.http import abort
 from util.saas.metricqueue import time_blueprint
-from util import get_app_url
-from app import app
-
+from auth.registry_jwt_auth import process_registry_jwt_auth, get_auth_headers
 
 logger = logging.getLogger(__name__)
 v2_bp = Blueprint('v2', __name__)
@@ -75,21 +72,15 @@ def route_show_if(value):
 
 @v2_bp.route('/')
 @route_show_if(features.ADVERTISE_V2)
-@process_jwt_auth
+@process_registry_jwt_auth
 @anon_allowed
 def v2_support_enabled():
   response = make_response('true', 200)
 
   if get_grant_context() is None:
     response = make_response('true', 401)
-    realm_auth_path = url_for('v2.generate_registry_jwt')
 
-    authenticate = 'Bearer realm="{0}{1}",service="{2}"'.format(get_app_url(app.config),
-                                                                realm_auth_path,
-                                                                app.config['SERVER_HOSTNAME'])
-    response.headers['WWW-Authenticate'] = authenticate
-
-  response.headers['Docker-Distribution-API-Version'] = 'registry/2.0'
+  response.headers.extend(get_auth_headers())
   return response