Retry callbacks on 429 'too many requests' code (#2155)

* Handle 429 'too many requests' differently with callbacks by retrying later

* Added comments on code intent.

* Run formatting on test file

app/celery/service_callback_tasks.py

@@ -65,31 +65,23 @@ def _send_data_to_service_callback_api(self, data, service_callback_url, token,
             data=json.dumps(data),
             headers={
                 "Content-Type": "application/json",
-                "Authorization": "Bearer {}".format(token),
+                "Authorization": f"Bearer {token}",
             },
             timeout=5,
         )
         current_app.logger.info(
-            "{} sending {} to {}, response {}".format(
-                function_name,
-                notification_id,
-                service_callback_url,
-                response.status_code,
-            )
+            f"{function_name} sending {notification_id} to {service_callback_url}, response {response.status_code}"
         )
         response.raise_for_status()
     except RequestException as e:
         current_app.logger.warning(
-            "{} request failed for notification_id: {} and url: {}. exc: {}".format(
-                function_name, notification_id, service_callback_url, e
-            )
+            f"{function_name} request failed for notification_id: {notification_id} and url: {service_callback_url}. exc: {e}"
         )
-        if not isinstance(e, HTTPError) or e.response.status_code >= 500:
+        # Retry if the response status code is server-side or 429 (too many requests).
+        if not isinstance(e, HTTPError) or e.response.status_code >= 500 or e.response.status_code == 429:
             try:
                 self.retry(queue=QueueNames.CALLBACKS_RETRY)
             except self.MaxRetriesExceededError:
                 current_app.logger.warning(
-                    "Retry: {} has retried the max num of times for callback url {} and notification_id: {}".format(
-                        function_name, service_callback_url, notification_id
-                    )
+                    "Retry: {function_name} has retried the max num of times for callback url {service_callback_url} and notification_id: {notification_id}"
                 )

tests/app/celery/test_service_callback_tasks.py

@@ -90,8 +90,9 @@ def test_send_complaint_to_service_posts_https_request_to_service_with_signed_da
 
 
 @pytest.mark.parametrize("notification_type", ["email", "letter", "sms"])
-def test__send_data_to_service_callback_api_retries_if_request_returns_500_with_signed_data(
-    notify_db_session, mocker, notification_type
+@pytest.mark.parametrize("status_code", [429, 500, 503])
+def test__send_data_to_service_callback_api_retries_if_request_returns_error_code_with_signed_data(
+    notify_db_session, mocker, notification_type, status_code
 ):
     callback_api, template = _set_up_test_data(notification_type, "delivery_status")
     datestr = datetime(2017, 6, 20)
@@ -107,7 +108,7 @@ def test__send_data_to_service_callback_api_retries_if_request_returns_500_with_
     signed_data = _set_up_data_for_status_update(callback_api, notification)
     mocked = mocker.patch("app.celery.service_callback_tasks.send_delivery_status_to_service.retry")
     with requests_mock.Mocker() as request_mock:
-        request_mock.post(callback_api.url, json={}, status_code=500)
+        request_mock.post(callback_api.url, json={}, status_code=status_code)
         send_delivery_status_to_service(notification.id, signed_status_update=signed_data)
 
     assert mocked.call_count == 1