fix(logger): improve behavior with exc_info=True to prevent errors (#6417)

fix exception logger

Author: leandrodamascena

aws_lambda_powertools/logging/formatter.py

@@ -357,19 +357,25 @@ def _extract_log_message(self, log_record: logging.LogRecord) -> dict[str, Any]
         return message
 
     def _serialize_stacktrace(self, log_record: logging.LogRecord) -> LogStackTrace | None:
-        if log_record.exc_info:
+        # Check if the first element of exc_info has the __name__ attribute,
+        # which indicates it is likely an exception class or object.
+        # See: https://github.com/aws-powertools/powertools-lambda-python/issues/6358
+        if isinstance(log_record.exc_info, tuple) and hasattr(log_record.exc_info[0], "__name__"):
             exception_info: LogStackTrace = {
                 "type": log_record.exc_info[0].__name__,  # type: ignore
                 "value": log_record.exc_info[1],  # type: ignore
                 "module": log_record.exc_info[1].__class__.__module__,
-                "frames": [],
+                "frames": [
+                    {
+                        "file": fs.filename,
+                        "line": fs.lineno,
+                        "function": fs.name,
+                        "statement": fs.line,
+                    }
+                    for fs in traceback.extract_tb(log_record.exc_info[2])
+                ],
             }
 
-            exception_info["frames"] = [
-                {"file": fs.filename, "line": fs.lineno, "function": fs.name, "statement": fs.line}
-                for fs in traceback.extract_tb(log_record.exc_info[2])
-            ]
-
             return exception_info
 
         return None
@@ -387,7 +393,7 @@ def _extract_log_exception(self, log_record: logging.LogRecord) -> tuple[str, st
         log_record: tuple[str, str] | tuple[None, None]
             Log record with constant traceback info and exception name
         """
-        if log_record.exc_info:
+        if isinstance(log_record.exc_info, tuple) and hasattr(log_record.exc_info[0], "__name__"):
             return self.formatException(log_record.exc_info), log_record.exc_info[0].__name__  # type: ignore
 
         return None, None

aws_lambda_powertools/utilities/parser/models/appsync.py

@@ -1,6 +1,8 @@
-from typing import Optional, List, Dict, Union, Any
+from typing import Any, Dict, List, Optional, Union
+
 from pydantic import BaseModel
 
+
 class AppSyncIamIdentity(BaseModel):
     accountId: str
     cognitoIdentityPoolId: Optional[str]
@@ -67,4 +69,4 @@ class AppSyncResolverEventModel(BaseModel):
     stash: Dict[str, Any]
 
 
-AppSyncBatchResolverEventModel = List[AppSyncResolverEventModel]
+AppSyncBatchResolverEventModel = List[AppSyncResolverEventModel]

tests/functional/logger/required_dependencies/test_logger.py

@@ -638,6 +638,19 @@ def test_logger_exception_extract_exception_name(stdout, service_name):
     assert "ValueError" == log["exception_name"]
 
 
+def test_logger_exception_should_not_fail_with_exception_block(stdout, service_name):
+    # GIVEN Logger is initialized
+    logger = Logger(service=service_name, stream=stdout)
+
+    # WHEN calling a logger.exception with a ValueError and outside of a try/except block
+    logger.exception("Received an exception")
+
+    # THEN the log output should not contain "exception_name" or "exception" and not fail
+    log = capture_logging_output(stdout)
+    assert "exception_name" not in log
+    assert "exception" not in log
+
+
 def test_logger_set_correlation_id(lambda_context, stdout, service_name):
     # GIVEN
     logger = Logger(service=service_name, stream=stdout)

tests/unit/parser/_pydantic/test_appsync.py

@@ -1,9 +1,10 @@
 import pytest
 
-from aws_lambda_powertools.utilities.parser import parse, ValidationError
+from aws_lambda_powertools.utilities.parser import ValidationError, parse
 from aws_lambda_powertools.utilities.parser.models import AppSyncResolverEventModel
 from tests.functional.utils import load_event
 
+
 def test_appsync_event_model_parses_successfully():
     """
     Validate that a valid AppSync resolver event is correctly parsed by the model.
@@ -24,4 +25,4 @@ def test_appsync_event_model_invalid_payload_raises():
     """
     invalid_event = {"invalid": "event"}
     with pytest.raises(ValidationError):
-        parse(event=invalid_event, model=AppSyncResolverEventModel)
+        parse(event=invalid_event, model=AppSyncResolverEventModel)