fix(langchain): ensure llm spans are created for sync cases

packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/__init__.py

@@ -5,6 +5,8 @@
 from opentelemetry.instrumentation.langchain.config import Config
 from wrapt import wrap_function_wrapper
 
+from opentelemetry import context as context_api
+
 from opentelemetry.trace import get_tracer
 
 from opentelemetry.instrumentation.instrumentor import BaseInstrumentor
@@ -24,7 +26,10 @@
 )
 
 from opentelemetry.metrics import get_meter
-from opentelemetry.semconv_ai import Meters
+from opentelemetry.semconv_ai import (
+    Meters,
+    SUPPRESS_LANGUAGE_MODEL_INSTRUMENTATION_KEY
+)
 
 logger = logging.getLogger(__name__)
 
@@ -176,8 +181,8 @@ def _uninstrument(self, **kwargs):
 
 
 class _BaseCallbackManagerInitWrapper:
-    def __init__(self, callback_manager: "TraceloopCallbackHandler"):
-        self._callback_manager = callback_manager
+    def __init__(self, callback_handler: "TraceloopCallbackHandler"):
+        self._callback_handler = callback_handler
 
     def __call__(
         self,
@@ -188,10 +193,14 @@ def __call__(
     ) -> None:
         wrapped(*args, **kwargs)
         for handler in instance.inheritable_handlers:
-            if isinstance(handler, type(self._callback_manager)):
+            if isinstance(handler, type(self._callback_handler)):
                 break
         else:
-            instance.add_handler(self._callback_manager, True)
+            # Add a property to the handler which indicates the CallbackManager instance.
+            # Since the CallbackHandler only propagates context for sync callbacks,
+            # we need a way to determine the type of CallbackManager being wrapped.
+            self._callback_handler._callback_manager = instance
+            instance.add_handler(self._callback_handler, True)
 
 
 # This class wraps a function call to inject tracing information (trace headers) into
@@ -227,4 +236,10 @@ def __call__(
             # Update kwargs to include the modified headers
             kwargs["extra_headers"] = extra_headers
 
+        # In legacy chains like LLMChain, suppressing model instrumentations
+        # within create_llm_span doesn't work, so this should helps as a fallback
+        context_api.attach(
+            context_api.set_value(SUPPRESS_LANGUAGE_MODEL_INSTRUMENTATION_KEY, True)
+        )
+
         return wrapped(*args, **kwargs)

packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/callback_handler.py

@@ -6,6 +6,8 @@
 
 from langchain_core.callbacks import (
     BaseCallbackHandler,
+    CallbackManager,
+    AsyncCallbackManager,
 )
 from langchain_core.messages import BaseMessage
 from langchain_core.outputs import LLMResult
@@ -80,7 +82,7 @@ def _set_request_params(span, kwargs, span_holder: SpanHolder):
 
     _set_span_attribute(span, SpanAttributes.LLM_REQUEST_MODEL, model)
     # response is not available for LLM requests (as opposed to chat)
-    _set_span_attribute(span, SpanAttributes.LLM_RESPONSE_MODEL, model)
+    _set_span_attribute(span, SpanAttributes.LLM_RESPONSE_MODEL, model or "unknown")
 
     if "invocation_params" in kwargs:
         params = (
@@ -370,6 +372,7 @@ def __init__(
         self.token_histogram = token_histogram
         self.spans: dict[UUID, SpanHolder] = {}
         self.run_inline = True
+        self._callback_manager: CallbackManager | AsyncCallbackManager = None
 
     @staticmethod
     def _get_name_from_callback(
@@ -399,6 +402,9 @@ def _end_span(self, span: Span, run_id: UUID) -> None:
             if child_span.end_time is None:  # avoid warning on ended spans
                 child_span.end()
         span.end()
+        token = self.spans[run_id].token
+        if token:
+            context_api.detach(token)
 
     def _create_span(
         self,
@@ -437,13 +443,17 @@ def _create_span(
         else:
             span = self.tracer.start_span(span_name, kind=kind)
 
+        token = None
+        # TODO: make this unconditional once attach/detach works properly with async callbacks.
+        # Currently, it doesn't work due to this - https://github.com/langchain-ai/langchain/issues/31398
+        # As a sidenote, OTel Python users also report similar issues -
+        # https://github.com/open-telemetry/opentelemetry-python/issues/2606
+        if self._callback_manager and not self._callback_manager.is_async:
+            token = context_api.attach(set_span_in_context(span))
+
         _set_span_attribute(span, SpanAttributes.TRACELOOP_WORKFLOW_NAME, workflow_name)
         _set_span_attribute(span, SpanAttributes.TRACELOOP_ENTITY_PATH, entity_path)
 
-        token = context_api.attach(
-            context_api.set_value(SUPPRESS_LANGUAGE_MODEL_INSTRUMENTATION_KEY, True)
-        )
-
         self.spans[run_id] = SpanHolder(
             span, token, None, [], workflow_name, entity_name, entity_path
         )
@@ -503,6 +513,16 @@ def _create_llm_span(
         _set_span_attribute(span, SpanAttributes.LLM_SYSTEM, "Langchain")
         _set_span_attribute(span, SpanAttributes.LLM_REQUEST_TYPE, request_type.value)
 
+        # we already have an LLM span by this point,
+        # so skip any downstream instrumentation from here
+        token = context_api.attach(
+            context_api.set_value(SUPPRESS_LANGUAGE_MODEL_INSTRUMENTATION_KEY, True)
+        )
+
+        self.spans[run_id] = SpanHolder(
+            span, token, None, [], workflow_name, None, entity_path
+        )
+
         return span
 
     @dont_throw
@@ -661,7 +681,7 @@ def on_llm_end(
                 "model_name"
             ) or response.llm_output.get("model_id")
             if model_name is not None:
-                _set_span_attribute(span, SpanAttributes.LLM_RESPONSE_MODEL, model_name)
+                _set_span_attribute(span, SpanAttributes.LLM_RESPONSE_MODEL, model_name or "unknown")
 
                 if self.spans[run_id].request_model is None:
                     _set_span_attribute(span, SpanAttributes.LLM_REQUEST_MODEL, model_name)