Add ability for triggers to be disabled

Will be used in the followup commit to automatically disable broken triggers

endpoints/webhooks.py

@@ -12,7 +12,8 @@ from util.http import abort
 from buildtrigger.basehandler import BuildTriggerHandler
 from buildtrigger.triggerutil import (ValidationRequestException, SkipRequestException,
                                       InvalidPayloadException)
-from endpoints.building import start_build, MaximumBuildsQueuedException
+from endpoints.building import (start_build, MaximumBuildsQueuedException,
+                                BuildTriggerDisabledException)
 
 
 logger = logging.getLogger(__name__)
@@ -91,9 +92,7 @@ def build_trigger_webhook(trigger_uuid, **kwargs):
 
   namespace = trigger.repository.namespace_user.username
   repository = trigger.repository.name
-  permission = ModifyRepositoryPermission(namespace, repository)
-
-  if permission.can():
+  if ModifyRepositoryPermission(namespace, repository).can():
     handler = BuildTriggerHandler.get_handler(trigger)
 
     if trigger.repository.kind.name != 'image':
@@ -121,6 +120,9 @@ def build_trigger_webhook(trigger_uuid, **kwargs):
       start_build(repo, prepared, pull_robot_name=pull_robot_name)
     except MaximumBuildsQueuedException:
       abort(429, message='Maximum queued build rate exceeded.')
+    except BuildTriggerDisabledException:
+      logger.debug('Build trigger %s is disabled', trigger_uuid)
+      abort(400, message='This build trigger is currently disabled. Please re-enable to continue.')
 
     return make_response('Okay')