Add flask exception information to span attributes (#1188)

Author: lzchen

contrib/opencensus-ext-flask/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- Add exception information to span attributes
+([#1188](https://github.com/census-instrumentation/opencensus-python/pull/1188))
+
 ## 0.8.1
 Released 2022-08-03
 

contrib/opencensus-ext-flask/opencensus/ext/flask/flask_middleware.py

@@ -16,6 +16,7 @@
 
 import logging
 import sys
+import traceback
 
 import flask
 from google.rpc import code_pb2
@@ -40,6 +41,9 @@
 HTTP_ROUTE = attributes_helper.COMMON_ATTRIBUTES['HTTP_ROUTE']
 HTTP_URL = attributes_helper.COMMON_ATTRIBUTES['HTTP_URL']
 HTTP_STATUS_CODE = attributes_helper.COMMON_ATTRIBUTES['HTTP_STATUS_CODE']
+ERROR_MESSAGE = attributes_helper.COMMON_ATTRIBUTES['ERROR_MESSAGE']
+ERROR_NAME = attributes_helper.COMMON_ATTRIBUTES['ERROR_NAME']
+STACKTRACE = attributes_helper.COMMON_ATTRIBUTES['STACKTRACE']
 
 EXCLUDELIST_PATHS = 'EXCLUDELIST_PATHS'
 EXCLUDELIST_HOSTNAMES = 'EXCLUDELIST_HOSTNAMES'
@@ -217,16 +221,28 @@ def _teardown_request(self, exception):
                         code=code_pb2.UNKNOWN,
                         message=str(exception)
                     )
-                    # try attaching the stack trace to the span, only populated
-                    # if the app has 'PROPAGATE_EXCEPTIONS', 'DEBUG', or
-                    # 'TESTING' enabled
-                    exc_type, _, exc_traceback = sys.exc_info()
+                    span.add_attribute(
+                        attribute_key=ERROR_NAME,
+                        attribute_value=exception.__class__.__name__)
+                    span.add_attribute(
+                        attribute_key=ERROR_MESSAGE,
+                        attribute_value=str(exception))
+
+                    if hasattr(exception, '__traceback__'):
+                        exc_traceback = exception.__traceback__
+                    else:
+                        exc_type, _, exc_traceback = sys.exc_info()
                     if exc_traceback is not None:
                         span.stack_trace = (
                             stack_trace.StackTrace.from_traceback(
                                 exc_traceback
                             )
                         )
+                        span.add_attribute(
+                            attribute_key=STACKTRACE,
+                            attribute_value='\n'.join(
+                                traceback.format_tb(exc_traceback))
+                        )
 
             tracer.end_span()
             tracer.finish()

contrib/opencensus-ext-flask/tests/test_flask_middleware.py

@@ -383,6 +383,13 @@ def test_teardown_include_exception(self):
             exported_spandata.status.canonical_code, code_pb2.UNKNOWN
         )
         self.assertEqual(exported_spandata.status.description, 'error')
+        self.assertEqual(
+            exported_spandata.attributes["error.name"], 'FlaskTestException'
+        )
+        self.assertEqual(
+            exported_spandata.attributes["error.message"], 'error'
+        )
+        self.assertIsNotNone(exported_spandata.attributes["error.message"])
 
     def test_teardown_include_exception_and_traceback(self):
         mock_exporter = mock.MagicMock()