Fix overwritten log attributes in vertexai instrumentation (#3925)

Author: aabmass

instrumentation-genai/opentelemetry-instrumentation-vertexai/CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
+- Fix overwritten log attributes in vertexai instrumentation
+  ([#3925](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3925))
 
 ## Version 2.1b0 (2025-10-16)
 

instrumentation-genai/opentelemetry-instrumentation-vertexai/src/opentelemetry/instrumentation/vertexai/patch.py

@@ -172,14 +172,15 @@ def handle_response(
                 | prediction_service_v1beta1.GenerateContentResponse
                 | None,
             ) -> None:
-                event = LogRecord(
-                    event_name="gen_ai.client.inference.operation.details",
-                )
                 attributes = (
                     get_server_attributes(instance.api_endpoint)  # type: ignore[reportUnknownMemberType]
                     | request_attributes
                     | get_genai_response_attributes(response)
                 )
+                event = LogRecord(
+                    event_name="gen_ai.client.inference.operation.details",
+                )
+                event.attributes = attributes.copy()
                 system_instructions, inputs, outputs = [], [], []
                 if params.system_instruction:
                     system_instructions = convert_content_to_message_parts(
@@ -237,7 +238,6 @@ def handle_response(
                                 for k, v in content_attributes.items()
                             }
                         )
-                event.attributes = attributes
                 if capture_content in (
                     ContentCapturingMode.SPAN_AND_EVENT,
                     ContentCapturingMode.EVENT_ONLY,

instrumentation-genai/opentelemetry-instrumentation-vertexai/tests/test_function_calling_experimental.py

@@ -274,6 +274,14 @@ def test_tool_events_with_completion_hook(
     assert len(logs) == 1
     # File upload takes a few seconds sometimes.
     time.sleep(3)
+
+    # Both log and span have the same reference attributes from upload hook
+    for key in "gen_ai.input.messages_ref", "gen_ai.output.messages_ref":
+        assert spans[0].attributes.get(key)
+        assert logs[0].log_record.attributes.get(key)
+
+        assert spans[0].attributes[key] == logs[0].log_record.attributes[key]
+
     assert_fsspec_equal(
         spans[0].attributes["gen_ai.output.messages_ref"],
         [