Add details in docs

docs/my-website/docs/observability/braintrust.md

@@ -75,6 +75,12 @@ It is recommended that you include the `project_id` or `project_name` to ensure
 
 You can customize the span name in Braintrust logging by passing `span_name` in the metadata. By default, the span name is set to "Chat Completion".
 
+### Custom Span Attributes
+
+You can customize the span id, root span name and span parents in Braintrust logging by passing `span_id`, `root_span_id` and `span_parents` in the metadata. 
+`span_parents` should be a string containing a list of span ids, joined by ,
+
+
 <Tabs>
 <TabItem value="sdk" label="SDK">
 

litellm/integrations/braintrust_logging.py

@@ -206,6 +206,20 @@ def log_success_event(  # noqa: PLR0915
 
             # Allow metadata override for span name
             span_name = dynamic_metadata.get("span_name", "Chat Completion")
+
+            # Span parents is a special case
+            span_parents = dynamic_metadata.get("span_parents")
+
+            # Convert comma-separated string to list if present
+            if span_parents:
+                span_parents = [s.strip() for s in span_parents.split(",") if s.strip()]
+
+            # Add optional span attributes only if present
+            span_attributes = {
+                "span_id": dynamic_metadata.get("span_id"),
+                "root_span_id": dynamic_metadata.get("root_span_id"),
+                "span_parents": span_parents,
+            }
 
             request_data = {
                 "id": litellm_call_id,
@@ -214,6 +228,12 @@ def log_success_event(  # noqa: PLR0915
                 "tags": tags,
                 "span_attributes": {"name": span_name, "type": "llm"},
             }
+
+            # Only add those that are not None (or falsy)
+            for key, value in span_attributes.items():
+                if value:
+                    request_data[key] = value
+
             if choices is not None:
                 request_data["output"] = [choice.dict() for choice in choices]
             else:

tests/test_litellm/integrations/test_braintrust_span_name.py

@@ -224,6 +224,76 @@ async def test_async_custom_span_name(self, mock_get_http_handler):
             json_data["events"][0]["span_attributes"]["name"], "Async Custom Operation"
         )
 
+    @patch('litellm.integrations.braintrust_logging.HTTPHandler')
+    def test_span_attributes_with_multiple_metadata_fields(self, MockHTTPHandler):
+        """Test that span_name works correctly alongside other metadata fields."""
+        # Mock HTTP response
+        mock_response = Mock()
+        mock_response.json.return_value = {"id": "test-project-id"}
+        mock_http_handler = Mock()
+        mock_http_handler.post.return_value = mock_response
+        MockHTTPHandler.return_value = mock_http_handler
+
+        # Setup
+        logger = BraintrustLogger(api_key="test-key")
+        logger.default_project_id = "test-project-id"
+
+        # Create a mock response object
+        message_mock = Mock()
+        message_mock.json = Mock(return_value={"content": "test"})
+
+        choice_mock = Mock()
+        choice_mock.message = message_mock
+        choice_mock.dict = Mock(return_value={"message": {"content": "test"}})
+        choice_mock.__getitem__ = Mock(return_value=message_mock)
+
+        response_obj = Mock(spec=litellm.ModelResponse)
+        response_obj.choices = [choice_mock]
+        response_obj.__getitem__ = Mock(return_value=[choice_mock])
+        response_obj.usage = litellm.Usage(
+            prompt_tokens=10,
+            completion_tokens=20,
+            total_tokens=30
+        )
+
+        kwargs = {
+            "litellm_call_id": "test-call-id",
+            "messages": [{"role": "user", "content": "test"}],
+            "litellm_params": {
+                "metadata": {
+                    "span_name": "Multi Metadata Test",
+                    "span_id": "span_id",
+                    "root_span_id": "root_span_id",
+                    "span_parents": "span_parent1,span_parent2",
+                    "project_id": "custom-project",
+                    "user_id": "user123",
+                    "session_id": "session456"
+                }
+            },
+            "model": "gpt-3.5-turbo",
+            "response_cost": 0.001
+        }
+
+        # Execute
+        logger.log_success_event(kwargs, response_obj, datetime.now(), datetime.now())
+
+        # Verify
+        call_args = mock_http_handler.post.call_args
+        self.assertIsNotNone(call_args)
+        json_data = call_args.kwargs['json']
+
+        # Check span name
+        self.assertEqual(json_data['events'][0]['span_attributes']['name'], 'Multi Metadata Test')
+        self.assertEqual(json_data['events'][0]['span_id'], 'span_id')
+        self.assertEqual(json_data['events'][0]['root_span_id'], 'root_span_id')
+        self.assertEqual(json_data['events'][0]['span_parents'][0], 'span_parent1')
+        self.assertEqual(json_data['events'][0]['span_parents'][1], 'span_parent2')
+
+        # Check that other metadata is preserved
+        event_metadata = json_data['events'][0]['metadata']
+        self.assertEqual(event_metadata['user_id'], 'user123')
+        self.assertEqual(event_metadata['session_id'], 'session456')
+
 
 if __name__ == "__main__":
     unittest.main()