fix(exception-handling): Fix handling of network and other non-status-code errors when polling for datafile (#287)

Author: benweissmann

README.md

@@ -176,7 +176,7 @@ Build and install the SDK with pip, using the following command:
 To get test dependencies installed, use a modified version of the
 install command:
 
-    pip install -e .[test]
+    pip install -e '.[test]'
 
 You can run all unit tests with:
 

optimizely/config_manager.py

@@ -344,9 +344,14 @@ def fetch_datafile(self):
         if self.last_modified:
             request_headers[enums.HTTPHeaders.IF_MODIFIED_SINCE] = self.last_modified
 
-        response = requests.get(
-            self.datafile_url, headers=request_headers, timeout=enums.ConfigManager.REQUEST_TIMEOUT,
-        )
+        try:
+            response = requests.get(
+                self.datafile_url, headers=request_headers, timeout=enums.ConfigManager.REQUEST_TIMEOUT,
+            )
+        except requests_exceptions.RequestException as err:
+            self.logger.error('Fetching datafile from {} failed. Error: {}'.format(self.datafile_url, str(err)))
+            return
+
         self._handle_response(response)
 
     @property
@@ -411,7 +416,12 @@ def fetch_datafile(self):
         if self.last_modified:
             request_headers[enums.HTTPHeaders.IF_MODIFIED_SINCE] = self.last_modified
 
-        response = requests.get(
-            self.datafile_url, headers=request_headers, timeout=enums.ConfigManager.REQUEST_TIMEOUT,
-        )
+        try:
+            response = requests.get(
+                self.datafile_url, headers=request_headers, timeout=enums.ConfigManager.REQUEST_TIMEOUT,
+            )
+        except requests_exceptions.RequestException as err:
+            self.logger.error('Fetching datafile from {} failed. Error: {}'.format(self.datafile_url, str(err)))
+            return
+
         self._handle_response(response)

tests/test_config_manager.py

@@ -394,8 +394,8 @@ def test_fetch_datafile(self, _):
         self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
         self.assertTrue(project_config_manager.is_running)
 
-    def test_fetch_datafile__exception_raised(self, _):
-        """ Test that config_manager keeps running if exception is raised when fetching datafile. """
+    def test_fetch_datafile__status_exception_raised(self, _):
+        """ Test that config_manager keeps running if status code exception is raised when fetching datafile. """
         class MockExceptionResponse(object):
             def raise_for_status(self):
                 raise requests.exceptions.RequestException('Error Error !!')
@@ -434,6 +434,45 @@ def raise_for_status(self):
         # Confirm that config manager keeps running
         self.assertTrue(project_config_manager.is_running)
 
+    def test_fetch_datafile__request_exception_raised(self, _):
+        """ Test that config_manager keeps running if a request exception is raised when fetching datafile. """
+        sdk_key = 'some_key'
+        mock_logger = mock.Mock()
+        with mock.patch('optimizely.config_manager.PollingConfigManager.fetch_datafile'):
+            project_config_manager = config_manager.PollingConfigManager(sdk_key=sdk_key, logger=mock_logger)
+        expected_datafile_url = enums.ConfigManager.DATAFILE_URL_TEMPLATE.format(sdk_key=sdk_key)
+        test_headers = {'Last-Modified': 'New Time'}
+        test_datafile = json.dumps(self.config_dict_with_features)
+        test_response = requests.Response()
+        test_response.status_code = 200
+        test_response.headers = test_headers
+        test_response._content = test_datafile
+        with mock.patch('requests.get', return_value=test_response):
+            project_config_manager.fetch_datafile()
+
+        self.assertEqual(test_headers['Last-Modified'], project_config_manager.last_modified)
+        self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
+
+        # Call fetch_datafile again, but raise exception this time
+        with mock.patch(
+            'requests.get',
+            side_effect=requests.exceptions.RequestException('Error Error !!'),
+        ) as mock_requests:
+            project_config_manager.fetch_datafile()
+
+        mock_requests.assert_called_once_with(
+            expected_datafile_url,
+            headers={'If-Modified-Since': test_headers['Last-Modified']},
+            timeout=enums.ConfigManager.REQUEST_TIMEOUT,
+        )
+        mock_logger.error.assert_called_once_with('Fetching datafile from {} failed. Error: Error Error !!'.format(
+            expected_datafile_url
+        ))
+        self.assertEqual(test_headers['Last-Modified'], project_config_manager.last_modified)
+        self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
+        # Confirm that config manager keeps running
+        self.assertTrue(project_config_manager.is_running)
+
     def test_is_running(self, _):
         """ Test that polling thread is running after instance of PollingConfigManager is created. """
         with mock.patch('optimizely.config_manager.PollingConfigManager.fetch_datafile'):
@@ -492,3 +531,58 @@ def test_fetch_datafile(self, _):
         )
 
         self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
+
+    def test_fetch_datafile__request_exception_raised(self, _):
+        """ Test that config_manager keeps running if a request exception is raised when fetching datafile. """
+        datafile_access_token = 'some_token'
+        sdk_key = 'some_key'
+        mock_logger = mock.Mock()
+
+        with mock.patch('optimizely.config_manager.AuthDatafilePollingConfigManager.fetch_datafile'):
+            project_config_manager = config_manager.AuthDatafilePollingConfigManager(
+                datafile_access_token=datafile_access_token, sdk_key=sdk_key, logger=mock_logger)
+        expected_datafile_url = enums.ConfigManager.AUTHENTICATED_DATAFILE_URL_TEMPLATE.format(sdk_key=sdk_key)
+        test_headers = {'Last-Modified': 'New Time'}
+        test_datafile = json.dumps(self.config_dict_with_features)
+        test_response = requests.Response()
+        test_response.status_code = 200
+        test_response.headers = test_headers
+        test_response._content = test_datafile
+
+        # Call fetch_datafile and assert that request was sent with correct authorization header
+        with mock.patch('requests.get',
+                        return_value=test_response) as mock_request:
+            project_config_manager.fetch_datafile()
+
+        mock_request.assert_called_once_with(
+            expected_datafile_url,
+            headers={'Authorization': 'Bearer {datafile_access_token}'.format(
+                datafile_access_token=datafile_access_token)},
+            timeout=enums.ConfigManager.REQUEST_TIMEOUT,
+        )
+
+        self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
+
+        # Call fetch_datafile again, but raise exception this time
+        with mock.patch(
+            'requests.get',
+            side_effect=requests.exceptions.RequestException('Error Error !!'),
+        ) as mock_requests:
+            project_config_manager.fetch_datafile()
+
+        mock_requests.assert_called_once_with(
+            expected_datafile_url,
+            headers={
+                'If-Modified-Since': test_headers['Last-Modified'],
+                'Authorization': 'Bearer {datafile_access_token}'.format(
+                    datafile_access_token=datafile_access_token),
+            },
+            timeout=enums.ConfigManager.REQUEST_TIMEOUT,
+        )
+        mock_logger.error.assert_called_once_with('Fetching datafile from {} failed. Error: Error Error !!'.format(
+            expected_datafile_url
+        ))
+        self.assertEqual(test_headers['Last-Modified'], project_config_manager.last_modified)
+        self.assertIsInstance(project_config_manager.get_config(), project_config.ProjectConfig)
+        # Confirm that config manager keeps running
+        self.assertTrue(project_config_manager.is_running)