feat(llmobs): improve langchain llmobs span names

ddtrace/llmobs/_constants.py

@@ -20,3 +20,5 @@
 SPAN_START_WHILE_DISABLED_WARNING = (
     "Span started while LLMObs is disabled." " Spans will not be sent to LLM Observability."
 )
+
+LANGCHAIN_APM_SPAN_NAME = "langchain.request"

ddtrace/llmobs/_trace_processor.py

@@ -33,6 +33,7 @@
 from ddtrace.llmobs._utils import _get_llmobs_parent_id
 from ddtrace.llmobs._utils import _get_ml_app
 from ddtrace.llmobs._utils import _get_session_id
+from ddtrace.llmobs._utils import _get_span_name
 
 
 log = get_logger(__name__)
@@ -105,7 +106,7 @@ def _llmobs_span_event(self, span: Span) -> Dict[str, Any]:
             "span_id": str(span.span_id),
             "parent_id": str(_get_llmobs_parent_id(span) or "undefined"),
             "session_id": session_id,
-            "name": span.name,
+            "name": _get_span_name(span),
             "tags": self._llmobs_tags(span, ml_app=ml_app, session_id=session_id),
             "start_ns": span.start_ns,
             "duration": span.duration_ns,

ddtrace/llmobs/_utils.py

@@ -3,6 +3,7 @@
 from ddtrace import Span
 from ddtrace import config
 from ddtrace.ext import SpanTypes
+from ddtrace.llmobs._constants import LANGCHAIN_APM_SPAN_NAME
 from ddtrace.llmobs._constants import ML_APP
 from ddtrace.llmobs._constants import SESSION_ID
 
@@ -27,6 +28,12 @@ def _get_llmobs_parent_id(span: Span) -> Optional[int]:
     return None
 
 
+def _get_span_name(span: Span) -> str:
+    if span.name == LANGCHAIN_APM_SPAN_NAME and span.resource != "":
+        return span.resource.lower()
+    return span.name
+
+
 def _get_ml_app(span: Span) -> str:
     """
     Return the ML app name for a given span, by checking the span's nearest LLMObs span ancestor.

tests/llmobs/_utils.py

@@ -159,7 +159,7 @@ def _llmobs_base_span_event(
         "trace_id": "{:x}".format(span.trace_id),
         "parent_id": _get_llmobs_parent_id(span),
         "session_id": session_id or "{:x}".format(span.trace_id),
-        "name": span.name,
+        "name": span.resource.lower(),
         "tags": _expected_llmobs_tags(span, tags=tags, error=error, session_id=session_id),
         "start_ns": span.start_ns,
         "duration": span.duration_ns,

tests/llmobs/test_llmobs_trace_processor.py

@@ -6,6 +6,7 @@
 from ddtrace.llmobs._constants import INPUT_MESSAGES
 from ddtrace.llmobs._constants import INPUT_PARAMETERS
 from ddtrace.llmobs._constants import INPUT_VALUE
+from ddtrace.llmobs._constants import LANGCHAIN_APM_SPAN_NAME
 from ddtrace.llmobs._constants import METADATA
 from ddtrace.llmobs._constants import METRICS
 from ddtrace.llmobs._constants import ML_APP
@@ -360,6 +361,17 @@ def test_metrics_are_set():
         assert tp._llmobs_span_event(llm_span)["metrics"] == {"tokens": 100}
 
 
+def test_langchain_span_name_is_set_to_class_name():
+    """Test span names for langchain auto-instrumented spans is set correctly."""
+    dummy_tracer = DummyTracer()
+    mock_llmobs_span_writer = mock.MagicMock()
+    with override_global_config(dict(_llmobs_ml_app="unnamed-ml-app")):
+        with dummy_tracer.trace(LANGCHAIN_APM_SPAN_NAME, resource="expected_name", span_type=SpanTypes.LLM) as llm_span:
+            llm_span.set_tag(SPAN_KIND, "llm")
+        tp = LLMObsTraceProcessor(llmobs_span_writer=mock_llmobs_span_writer)
+        assert tp._llmobs_span_event(llm_span)["name"] == "expected_name"
+
+
 def test_error_is_set():
     """Test that error is set on the span event if it is present on the span."""
     dummy_tracer = DummyTracer()