fix: no duplicate logs on GCF or GAE (#209)

Author: daniel-sanche

google/cloud/logging_v2/client.py

@@ -52,6 +52,7 @@
 
 _GAE_RESOURCE_TYPE = "gae_app"
 _GKE_RESOURCE_TYPE = "k8s_container"
+_GCF_RESOURCE_TYPE = "cloud_function"
 
 
 class Client(ClientWithProject):

google/cloud/logging_v2/handlers/_monitored_resources.py

@@ -163,7 +163,7 @@ def _create_global_resource(project):
     return Resource(type="global", labels={"project_id": project})
 
 
-def detect_resource(project):
+def detect_resource(project=""):
     """Return the default monitored resource based on the local environment.
     Args:
         project (str): The project ID to pass on to the resource

google/cloud/logging_v2/handlers/handlers.py

@@ -23,6 +23,8 @@
 
 EXCLUDED_LOGGER_DEFAULTS = ("google.cloud", "google.auth", "google_auth_httplib2")
 
+_CLEAR_HANDLER_RESOURCE_TYPES = ("gae_app", "cloud_function")
+
 
 class CloudLoggingHandler(logging.StreamHandler):
     """Handler that directly makes Cloud Logging API calls.
@@ -160,6 +162,11 @@ def setup_logging(
     """
     all_excluded_loggers = set(excluded_loggers + EXCLUDED_LOGGER_DEFAULTS)
     logger = logging.getLogger()
+
+    # remove built-in handlers on App Engine or Cloud Functions environments
+    if detect_resource().type in _CLEAR_HANDLER_RESOURCE_TYPES:
+        logger.handlers.clear()
+
     logger.setLevel(log_level)
     logger.addHandler(handler)
     for logger_name in all_excluded_loggers:

tests/environment

@@ -14,8 +14,14 @@
 
 import logging
 import unittest
+from unittest.mock import patch
 import mock
 
+from google.cloud.logging_v2.handlers._monitored_resources import (
+    _FUNCTION_ENV_VARS,
+    _GAE_ENV_VARS,
+)
+
 
 class TestCloudLoggingHandler(unittest.TestCase):
 
@@ -165,6 +171,49 @@ def test_setup_logging_excludes(self):
         self.assertNotIn(handler, excluded_logger.handlers)
         self.assertFalse(excluded_logger.propagate)
 
+    @patch.dict("os.environ", {envar: "1" for envar in _FUNCTION_ENV_VARS})
+    def test_remove_handlers_gcf(self):
+        logger = logging.getLogger()
+        # add fake handler
+        added_handler = logging.StreamHandler()
+        logger.addHandler(added_handler)
+
+        handler = _Handler(logging.INFO)
+        self._call_fut(handler)
+        self.assertNotIn(added_handler, logger.handlers)
+        # handler should be removed from logger
+        self.assertEqual(len(logger.handlers), 1)
+
+    @patch.dict("os.environ", {envar: "1" for envar in _GAE_ENV_VARS})
+    def test_remove_handlers_gae(self):
+        logger = logging.getLogger()
+        # add fake handler
+        added_handler = logging.StreamHandler()
+        logger.addHandler(added_handler)
+
+        handler = _Handler(logging.INFO)
+        self._call_fut(handler)
+        self.assertNotIn(added_handler, logger.handlers)
+        # handler should be removed from logger
+        self.assertEqual(len(logger.handlers), 1)
+
+    def test_keep_handlers_others(self):
+        # mock non-cloud environment
+        patch = mock.patch(
+            "google.cloud.logging_v2.handlers._monitored_resources.retrieve_metadata_server",
+            return_value=None,
+        )
+        with patch:
+            # add fake handler
+            added_handler = logging.StreamHandler()
+            logger = logging.getLogger()
+            logger.addHandler(added_handler)
+
+            handler = _Handler(logging.INFO)
+            self._call_fut(handler)
+            # added handler should remain in logger
+            self.assertIn(added_handler, logger.handlers)
+
     def setUp(self):
         self._handlers_cache = logging.getLogger().handlers[:]