Integrated Celery startup / management / config with PillarServer.

pillar/extension.py

@@ -16,6 +16,7 @@ can then be registered to the application at app creation time:
 """
 
 import abc
+import typing
 
 import flask
 import pillarsdk
@@ -25,6 +26,9 @@ class PillarExtension(object, metaclass=abc.ABCMeta):
     # Set to True when your extension implements the project_settings() method.
     has_project_settings = False
 
+    # List of Celery task modules introduced by this extension.
+    celery_task_modules: typing.List[str] = []
+
     @property
     @abc.abstractmethod
     def name(self):