feat: add observability for default auth classes (openedx#33003)

Added new authentication classes to be used in
DEFAULT_AUTHENTICATION_CLASSES that include
observability. This will enable us to see more
about the endpoints using the defaults, to help
us make choices about changes in the defaults.

We make the DRF default of Session and Basic
Authentication explicit by setting
DEFAULT_AUTHENTICATION_CLASSES explicitly.

lms/envs/common.py

@@ -3286,6 +3286,13 @@ def _make_locale_paths(settings):  # pylint: disable=missing-function-docstring
 ######################### Django Rest Framework ########################
 
 REST_FRAMEWORK = {
+    # This matches the original DRF default of Session and Basic Authentication, but
+    # adds observability to help us potentially adjust the defaults. We would like to
+    # add JwtAuthentication and drop BasicAuthentication, based on our findings.
+    'DEFAULT_AUTHENTICATION_CLASSES': [
+        'openedx.core.djangolib.default_auth_classes.DefaultSessionAuthentication',
+        'openedx.core.djangolib.default_auth_classes.DefaultBasicAuthentication'
+    ],
     'DEFAULT_PAGINATION_CLASS': 'edx_rest_framework_extensions.paginators.DefaultPagination',
     'DEFAULT_RENDERER_CLASSES': (
         'rest_framework.renderers.JSONRenderer',
@@ -3303,7 +3310,7 @@ def _make_locale_paths(settings):  # pylint: disable=missing-function-docstring
 
 # .. setting_name: REGISTRATION_VALIDATION_RATELIMIT
 # .. setting_default: 30/7d
-# .. setting_description: Whenver a user tries to register on edx, the data entered during registration
+# .. setting_description: Whenever a user tries to register on edx, the data entered during registration
 #    is validated via RegistrationValidationView.
 #    It's POST endpoint is rate-limited up to 30 requests per IP Address in a week by default.
 #    It was introduced because an attacker can guess or brute force a series of names to enumerate valid users.

openedx/core/djangolib/default_auth_classes.py

@@ -0,0 +1,87 @@
+"""
+Default Authentication classes that are ONLY meant to be used by
+DEFAULT_AUTHENTICATION_CLASSES for observability purposes.
+"""
+from edx_django_utils.monitoring import set_custom_attribute
+from edx_rest_framework_extensions.auth.jwt.authentication import JwtAuthentication
+from rest_framework.authentication import BasicAuthentication, SessionAuthentication
+
+
+class DefaultSessionAuthentication(SessionAuthentication):
+    """ Default SessionAuthentication with observability """
+
+    def authenticate(self, request):
+        # .. custom_attribute_name: using_default_auth_classes
+        # .. custom_attribute_description: This custom attribute will always be
+        #     True (if not NULL), and signifies that a default authentication
+        #     class was used. This can be used to find endpoints using the
+        #     default authentication classes.
+        set_custom_attribute('using_default_auth_classes', True)
+
+        try:
+            user_and_auth = super().authenticate(request)
+            if user_and_auth:
+                # .. custom_attribute_name: session_auth_result
+                # .. custom_attribute_description: The result of session auth, represented
+                #      by: 'success', 'failure', or 'skipped'.
+                set_custom_attribute('session_auth_result', 'success')
+            else:
+                set_custom_attribute('session_auth_result', 'skipped')
+            return user_and_auth
+        except Exception as exception:
+            set_custom_attribute('session_auth_result', 'failure')
+            raise
+
+
+class DefaultBasicAuthentication(BasicAuthentication):
+    """
+    Default BasicAuthentication with observability
+
+    Note that BasicAuthentication was a default because it was a DRF default.
+    Observability will be used to determine if BasicAuthentication could
+    instead be dropped as a default.
+    """
+
+    def authenticate(self, request):
+        # .. custom_attribute_name: using_default_auth_classes
+        # .. custom_attribute_description: This custom attribute will always be
+        #     True (if not NULL), and signifies that a default authentication
+        #     class was used. This can be used to find endpoints using the
+        #     default authentication classes.
+        set_custom_attribute('using_default_auth_classes', True)
+
+        try:
+            user_and_auth = super().authenticate(request)
+            if user_and_auth:
+                # .. custom_attribute_name: basic_auth_result
+                # .. custom_attribute_description: The result of basic auth, represented
+                #      by: 'success', 'failure', or 'skipped'.
+                set_custom_attribute('basic_auth_result', 'success')
+            else:
+                set_custom_attribute('basic_auth_result', 'skipped')
+            return user_and_auth
+        except Exception as exception:
+            set_custom_attribute('basic_auth_result', 'failure')
+            raise
+
+
+class DefaultJwtAuthentication(JwtAuthentication):
+    """
+    Default JwtAuthentication with observability
+
+    Note that the plan is to add JwtAuthentication as a default, but it
+    is not yet used. This class will be used during the transition.
+    """
+
+    def authenticate(self, request):
+        # .. custom_attribute_name: using_default_auth_classes
+        # .. custom_attribute_description: This custom attribute will always be
+        #     True (if not NULL), and signifies that a default authentication
+        #     class was used. This can be used to find endpoints using the
+        #     default authentication classes.
+        set_custom_attribute('using_default_auth_classes', True)
+
+        # Unlike the other DRF authentication classes, JwtAuthentication already
+        # includes a jwt_auth_result custom attribute, so we do not need to
+        # reimplement that observability in this class.
+        return super().authenticate(request)