fix: reorder JWT decoders

ecommerce/extensions/api/handlers.py

@@ -5,8 +5,6 @@
 custom jwt_decode_handler.
 
 """
-
-
 import logging
 
 import jwt
@@ -18,8 +16,6 @@
 
 logger = logging.getLogger(__name__)
 
-JWT_DECODE_HANDLER_METRIC_KEY = 'ecom_jwt_decode_handler'
-
 
 def _ecommerce_jwt_decode_handler_multiple_issuers(token):
     """
@@ -94,26 +90,31 @@ def jwt_decode_handler(token):
 
     """
 
-    # First, try ecommerce decoder that handles multiple issuers.
-    # See ARCH-276 for details of removing additional issuers and retiring this
-    # custom jwt_decode_handler.
-    try:
-        jwt_payload = _ecommerce_jwt_decode_handler_multiple_issuers(token)
-        monitoring_utils.set_custom_metric(JWT_DECODE_HANDLER_METRIC_KEY, 'ecommerce-multiple-issuers')
-        return jwt_payload
-    except Exception:  # pylint: disable=broad-except
-        if waffle.switch_is_active('jwt_decode_handler.log_exception.ecommerce-multiple-issuers'):
-            logger.info('Failed to use ecommerce multiple issuer jwt_decode_handler.', exc_info=True)
-
-    # Next, try jwt_decode_handler from edx_drf_extensions
+    # First, try jwt_decode_handler from edx_drf_extensions
     # Note: this jwt_decode_handler can handle asymmetric keys, but only a
     #   single issuer. Therefore, the LMS must be the first configured issuer.
     try:
         jwt_payload = edx_drf_extensions_jwt_decode_handler(token)
-        monitoring_utils.set_custom_metric(JWT_DECODE_HANDLER_METRIC_KEY, 'edx-drf-extensions')
+        # Note: use increment in case there are multiple calls for different JWTs in the same transaction.
+        monitoring_utils.increment("ecom_jwt_decode_standard")
         return jwt_payload
     except Exception:  # pylint: disable=broad-except
         # continue and try again
         if waffle.switch_is_active('jwt_decode_handler.log_exception.edx-drf-extensions'):
             logger.info('Failed to use edx-drf-extensions jwt_decode_handler.', exc_info=True)
+
+    # Next, try ecommerce decoder that handles multiple issuers.
+    # See ARCH-276 for details of removing additional issuers and retiring this
+    # custom jwt_decode_handler.
+    try:
+        jwt_payload = _ecommerce_jwt_decode_handler_multiple_issuers(token)
+        # Ultimately we want there to be no JWTs that aren't handled by the first case.
+        #   This enables monitoring to see if there are still cases where the custom JWT
+        #   decoder is in use.
+        monitoring_utils.increment("ecom_jwt_decode_custom")
+        return jwt_payload
+    except Exception:  # pylint: disable=broad-except
+        if waffle.switch_is_active('jwt_decode_handler.log_exception.ecommerce-multiple-issuers'):
+            logger.info('Failed to use ecommerce multiple issuer jwt_decode_handler.', exc_info=True)
+        monitoring_utils.increment("ecom_jwt_decode_failed")
         raise

ecommerce/extensions/api/tests/test_handlers.py

@@ -49,9 +49,9 @@ def setUp(self):
             'JWT_VERIFY_AUDIENCE': False,
         }
     )
-    @mock.patch('edx_django_utils.monitoring.set_custom_metric')
+    @mock.patch('edx_django_utils.monitoring.increment')
     @mock.patch('ecommerce.extensions.api.handlers._ecommerce_jwt_decode_handler_multiple_issuers')
-    def test_decode_success_edx_drf_extensions(self, mock_multiple_issuer_decoder, mock_set_custom_metric):
+    def test_decode_success_edx_drf_extensions(self, mock_multiple_issuer_decoder, mock_increment):
         """
         Should pass using the edx-drf-extensions jwt_decode_handler.
 
@@ -63,7 +63,7 @@ def test_decode_success_edx_drf_extensions(self, mock_multiple_issuer_decoder, m
         payload = generate_jwt_payload(self.user, issuer_name=first_issuer['ISSUER'])
         token = generate_jwt_token(payload, first_issuer['SECRET_KEY'])
         self.assertDictContainsSubset(payload, jwt_decode_handler(token))
-        mock_set_custom_metric.assert_called_with('ecom_jwt_decode_handler', 'edx-drf-extensions')
+        mock_increment.assert_called_with('ecom_jwt_decode_standard')
 
     @override_settings(
         JWT_AUTH={
@@ -87,9 +87,9 @@ def test_decode_success_edx_drf_extensions(self, mock_multiple_issuer_decoder, m
             'JWT_VERIFY_AUDIENCE': False,
         }
     )
-    @mock.patch('edx_django_utils.monitoring.set_custom_metric')
+    @mock.patch('edx_django_utils.monitoring.increment')
     @mock.patch('ecommerce.extensions.api.handlers.logger')
-    def test_decode_success_multiple_issuers(self, mock_logger, mock_set_custom_metric):
+    def test_decode_success_multiple_issuers(self, mock_logger, mock_increment):
         """
         Should pass using ``_ecommerce_jwt_decode_handler_multiple_issuers``.
 
@@ -101,7 +101,7 @@ def test_decode_success_multiple_issuers(self, mock_logger, mock_set_custom_metr
         payload = generate_jwt_payload(self.user, issuer_name=non_first_issuer['ISSUER'])
         token = generate_jwt_token(payload, non_first_issuer['SECRET_KEY'])
         self.assertDictContainsSubset(payload, jwt_decode_handler(token))
-        mock_set_custom_metric.assert_called_with('ecom_jwt_decode_handler', 'ecommerce-multiple-issuers')
+        mock_increment.assert_called_with('ecom_jwt_decode_custom')
         mock_logger.exception.assert_not_called()
         mock_logger.warning.assert_not_called()
         mock_logger.error.assert_not_called()
@@ -141,6 +141,6 @@ def test_decode_error_invalid_token(self, mock_logger):
 
         mock_logger.exception.assert_called_with('Custom config JWT decode failed!')
         mock_logger.info.assert_has_calls(calls=[
-            mock.call('Failed to use ecommerce multiple issuer jwt_decode_handler.', exc_info=True),
             mock.call('Failed to use edx-drf-extensions jwt_decode_handler.', exc_info=True),
+            mock.call('Failed to use ecommerce multiple issuer jwt_decode_handler.', exc_info=True),
         ])