feat: refactor code_owner code from edx-dajango-utils (#838)

Initial rollout of moving code_owner monitoring code from
edx-django-utils to this plugin.

- Adds near duplicate of code owner middleware from
  edx-django-utils.
- Adds code owner span tags for celery using Datadog span
  processing of celery.run spans.
- Uses temporary span tags names using `_2`, like `code_owner_2`,
  for rollout and comparison with the original span tags.
- Span tag code_owner_2_module includes the task name, where
  the original code_owner_module does not. In both cases, the
  code owner is computed the same, because it is based on a prefix match.

See #784

CHANGELOG.rst

@@ -14,6 +14,17 @@ Change Log
 Unreleased
 ~~~~~~~~~~
 
+[5.1.0] - 2024-11-21
+~~~~~~~~~~~~~~~~~~~~
+Added
+-----
+* Added Datadog monitoring app which adds code owner monitoring. This is the first step in moving code owner code from edx-django-utils to this plugin.
+
+  * Adds near duplicate of code owner middleware from edx-django-utils.
+  * Adds code owner span tags for celery using Datadog span processing of celery.run spans.
+  * Uses temporary span tags names using ``_2``, like ``code_owner_2``, for rollout and comparison with the original span tags.
+  * Span tag code_owner_2_module includes the task name, where the original code_owner_module does not. In both cases, the code owner is computed the same, because it is based on a prefix match.
+
 [5.0.0] - 2024-10-22
 ~~~~~~~~~~~~~~~~~~~~
 Removed

edx_arch_experiments/__init__.py

@@ -2,4 +2,4 @@
 A plugin to include applications under development by the architecture team at 2U.
 """
 
-__version__ = '5.0.0'
+__version__ = '5.1.0'

edx_arch_experiments/datadog_monitoring/README.rst

@@ -0,0 +1,6 @@
+Datadog Monitoring
+###################
+
+When installed in the LMS as a plugin app, the ``datadog_monitoring`` app adds additional monitoring.
+
+This is where our code_owner_2 monitoring code lives, for example.

edx_arch_experiments/datadog_monitoring/apps.py

@@ -0,0 +1,19 @@
+"""
+App for 2U-specific edx-platform Datadog monitoring.
+"""
+from django.apps import AppConfig
+
+
+class DatadogMonitoring(AppConfig):
+    """
+    Django application to handle 2U-specific Datadog monitoring.
+    """
+    name = 'edx_arch_experiments.datadog_monitoring'
+
+    # Mark this as a plugin app
+    plugin_app = {}
+
+    def ready(self):
+        # Implicitly connect signal handlers decorated with @receiver
+        # pylint: disable=import-outside-toplevel,unused-import
+        from edx_arch_experiments.datadog_monitoring.signals import handlers

edx_arch_experiments/datadog_monitoring/code_owner/__init__.py

@@ -0,0 +1,6 @@
+"""
+This directory should only be used internally.
+
+Its public API is exposed in the top-level monitoring __init__.py.
+See its README.rst for details.
+"""

edx_arch_experiments/datadog_monitoring/code_owner/datadog.py

@@ -0,0 +1,26 @@
+"""
+Datadog span processor for celery span code owners.
+"""
+from .utils import set_code_owner_attribute_from_module
+
+
+class CeleryCodeOwnerSpanProcessor:
+    """
+    Datadog span processor that adds celery code owner span tags.
+    """
+
+    def on_span_start(self, span):
+        """
+        Adds code owner span tag for celery run spans at span creation.
+        """
+        if getattr(span, 'name', None) == 'celery.run':
+            # We can use this for celery spans, because the resource name is more predictable
+            # and available from the start. For django requests, we'll instead continue to use
+            # django middleware for setting code owner.
+            set_code_owner_attribute_from_module(span.resource)
+
+    def on_span_finish(self, span):
+        pass
+
+    def shutdown(self, _timeout):
+        pass

edx_arch_experiments/datadog_monitoring/code_owner/middleware.py

@@ -0,0 +1,89 @@
+"""
+Middleware for code_owner_2 custom attribute
+"""
+import logging
+
+from django.urls import resolve
+from edx_django_utils.monitoring import set_custom_attribute
+
+from .utils import get_code_owner_from_module, is_code_owner_mappings_configured, set_code_owner_custom_attributes
+
+log = logging.getLogger(__name__)
+
+
+class CodeOwnerMonitoringMiddleware:
+    """
+    Django middleware object to set custom attributes for the owner of each view.
+
+    For instructions on usage, see:
+    https://github.com/edx/edx-arch-experiments/blob/master/edx_arch_experiments/datadog_monitoring/docs/how_tos/add_code_owner_custom_attribute_to_an_ida.rst
+
+    Custom attributes set:
+    - code_owner_2: The owning team mapped to the current view.
+    - code_owner_2_module: The module found from the request or current transaction.
+    - code_owner_2_path_error: The error mapping by path, if code_owner_2 isn't found in other ways.
+
+    """
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        response = self.get_response(request)
+        self._set_code_owner_attribute(request)
+        return response
+
+    def process_exception(self, request, exception):    # pylint: disable=W0613
+        self._set_code_owner_attribute(request)
+
+    def _set_code_owner_attribute(self, request):
+        """
+        Sets the code_owner_2 custom attribute for the request.
+        """
+        code_owner = None
+        module = self._get_module_from_request(request)
+        if module:
+            code_owner = get_code_owner_from_module(module)
+
+        if code_owner:
+            set_code_owner_custom_attributes(code_owner)
+
+    def _get_module_from_request(self, request):
+        """
+        Get the module from the request path or the current transaction.
+
+        Side-effects:
+            Sets code_owner_2_module custom attribute, used to determine code_owner_2.
+            If module was not found, may set code_owner_2_path_error custom attribute
+                if applicable.
+
+        Returns:
+            str: module name or None if not found
+
+        """
+        if not is_code_owner_mappings_configured():
+            return None
+
+        module, path_error = self._get_module_from_request_path(request)
+        if module:
+            set_custom_attribute('code_owner_2_module', module)
+            return module
+
+        # monitor errors if module was not found
+        if path_error:
+            set_custom_attribute('code_owner_2_path_error', path_error)
+        return None
+
+    def _get_module_from_request_path(self, request):
+        """
+        Uses the request path to get the view_func module.
+
+        Returns:
+            (str, str): (module, error_message), where at least one of these should be None
+
+        """
+        try:
+            view_func, _, _ = resolve(request.path)
+            module = view_func.__module__
+            return module, None
+        except Exception as e:  # pragma: no cover, pylint: disable=broad-exception-caught
+            return None, str(e)