opentelemetry-sdk: fix serialization of objects in log handler

CHANGELOG.md

@@ -20,7 +20,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Patch logging.basicConfig so OTel logs don't cause console logs to disappear
   ([#4436](https://github.com/open-telemetry/opentelemetry-python/pull/4436))
 - Fix ExplicitBucketHistogramAggregation to handle multiple explicit bucket boundaries advisories
- ([#4521](https://github.com/open-telemetry/opentelemetry-python/pull/4521))
+  ([#4521](https://github.com/open-telemetry/opentelemetry-python/pull/4521))
+- opentelemetry-sdk: Fix serialization of objects in log handler
+  ([#4528](https://github.com/open-telemetry/opentelemetry-python/pull/4528))
 
 ## Version 1.31.0/0.52b0 (2025-03-12)
 

opentelemetry-api/src/opentelemetry/attributes/__init__.py

@@ -16,13 +16,24 @@
 import threading
 from collections import OrderedDict
 from collections.abc import MutableMapping
-from typing import Optional, Sequence, Tuple, Union
+from typing import Mapping, Optional, Sequence, Tuple, Union
 
 from opentelemetry.util import types
 
 # bytes are accepted as a user supplied value for attributes but
 # decoded to strings internally.
 _VALID_ATTR_VALUE_TYPES = (bool, str, bytes, int, float)
+# AnyValue possible values
+_VALID_ANY_VALUE_TYPES = (
+    type(None),
+    bool,
+    bytes,
+    int,
+    float,
+    str,
+    Sequence,
+    Mapping,
+)
 
 
 _logger = logging.getLogger(__name__)

opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py

@@ -36,7 +36,7 @@
     get_logger_provider,
     std_to_otel,
 )
-from opentelemetry.attributes import BoundedAttributes
+from opentelemetry.attributes import _VALID_ANY_VALUE_TYPES, BoundedAttributes
 from opentelemetry.sdk.environment_variables import (
     OTEL_ATTRIBUTE_COUNT_LIMIT,
     OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT,
@@ -523,8 +523,11 @@ def _translate(self, record: logging.LogRecord) -> LogRecord:
             # itself instead of its string representation.
             # For more background, see: https://github.com/open-telemetry/opentelemetry-python/pull/4216
             if not record.args and not isinstance(record.msg, str):
-                # no args are provided so it's *mostly* safe to use the message template as the body
-                body = record.msg
+                #  if record.msg is not a value we can export, cast it to string
+                if not isinstance(record.msg, _VALID_ANY_VALUE_TYPES):
+                    body = str(record.msg)
+                else:
+                    body = record.msg
             else:
                 body = record.getMessage()
 

opentelemetry-sdk/tests/logs/test_handler.py

@@ -153,6 +153,7 @@ def test_log_record_exception(self):
         log_record = processor.get_log_record(0)
 
         self.assertIsNotNone(log_record)
+        self.assertTrue(isinstance(log_record.body, str))
         self.assertEqual(log_record.body, "Zero Division Error")
         self.assertEqual(
             log_record.attributes[SpanAttributes.EXCEPTION_TYPE],
@@ -226,6 +227,47 @@ def test_log_exc_info_false(self):
             SpanAttributes.EXCEPTION_STACKTRACE, log_record.attributes
         )
 
+    def test_log_record_exception_with_object_payload(self):
+        processor, logger = set_up_test_logging(logging.ERROR)
+
+        class CustomObject:
+            pass
+
+        class CustomException(Exception):
+            def __init__(self, data):
+                self.data = data
+
+            def __str__(self):
+                return "CustomException stringified"
+
+        try:
+            raise CustomException(CustomObject())
+        except CustomException as exception:
+            with self.assertLogs(level=logging.ERROR):
+                logger.exception(exception)
+
+        log_record = processor.get_log_record(0)
+
+        self.assertIsNotNone(log_record)
+        self.assertTrue(isinstance(log_record.body, str))
+        self.assertEqual(log_record.body, "CustomException stringified")
+        self.assertEqual(
+            log_record.attributes[SpanAttributes.EXCEPTION_TYPE],
+            CustomException.__name__,
+        )
+        self.assertTrue(
+            "<tests.logs.test_handler.TestLoggingHandler.test_log_record_exception_with_object_payload.<locals>.CustomObject"
+            in log_record.attributes[SpanAttributes.EXCEPTION_MESSAGE]
+        )
+        stack_trace = log_record.attributes[
+            SpanAttributes.EXCEPTION_STACKTRACE
+        ]
+        self.assertIsInstance(stack_trace, str)
+        self.assertTrue("Traceback" in stack_trace)
+        self.assertTrue("CustomException" in stack_trace)
+        self.assertTrue("CustomObject" in stack_trace)
+        self.assertTrue(__file__ in stack_trace)
+
     def test_log_record_trace_correlation(self):
         processor, logger = set_up_test_logging(logging.WARNING)