CH-67 Change listener initialization to use a singleton and the setup_event_service call idempotent

Author: condar-metacell

infrastructure/common-images/cloudharness-django/libraries/cloudharness-django/cloudharness_django/services/events.py

@@ -15,6 +15,7 @@ class KeycloakMessageService:
     def __init__(self, kafka_group_id):
         self._topic = "keycloak.fct.admin"
         self.kafka_group_id = kafka_group_id
+        self.topics_initialized = False
 
     @staticmethod
     def event_handler(app, event_client, message):
@@ -50,6 +51,9 @@ def event_handler(app, event_client, message):
                 raise e
 
     def init_topics(self):
+        if self.topics_initialized:
+            return
+
         log.info("Starting Kafka consumer threads")
         try:
             event_client = EventClient(self._topic)
@@ -59,6 +63,7 @@ def init_topics(self):
             except TopicAlreadyExistsError as e:
                 pass
             event_client.async_consume(app={}, group_id=self.kafka_group_id, handler=KeycloakMessageService.event_handler)
+            self.topics_initialized = True
         except Exception as e:
             log.error(f"Error creating topic {self._topic}", exc_info=e)
 
@@ -79,8 +84,15 @@ def setup_event_service(self):
             pass
 
 
+_message_service_singleton = None
+
+
 def init_listener():
     if not hasattr(settings, "PROJECT_NAME"):
         raise KeycloakOIDCNoProjectError("Project name not found, please set PROJECT_NAME in your settings module")
 
-    KeycloakMessageService(settings.PROJECT_NAME).setup_event_service()
+    global _message_service_singleton
+    if _message_service_singleton is None:
+        _message_service_singleton = KeycloakMessageService(settings.PROJECT_NAME).setup_event_service()
+
+    _message_service_singleton.setup_event_service()