refactor(langfuse): read the sdk version header from package metadata

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/integrations/langfuse/langfuse_sdk.py

@@ -9,6 +9,7 @@ from contextlib import contextmanager
 from contextvars import ContextVar
 from datetime import datetime
 from hashlib import sha256
+from importlib.metadata import version
 from types import MappingProxyType
 from typing import Final
 from weakref import WeakKeyDictionary, WeakSet
@@ -448,11 +449,8 @@ def _build_verified_span_exporter(*, public_key: object, secret_key: object, bas
     client_certificate: Final = configured_certificate if isinstance(configured_certificate, str) else None
     if ca_bundle is None and client_certificate is None:
         return None
-    import langfuse as langfuse_package
     from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
 
-    langfuse_version: Final = getattr(langfuse_package, "__version__", "unknown")
-
     export_path: Final = os.getenv("LANGFUSE_OTEL_TRACES_EXPORT_PATH")
     endpoint: Final = f"{base_url}/{export_path}" if export_path else f"{base_url}/api/public/otel/v1/traces"
     encoded_auth: Final = b64encode(f"{public_key}:{secret_key}".encode()).decode("ascii")
@@ -461,7 +459,7 @@ def _build_verified_span_exporter(*, public_key: object, secret_key: object, bas
         headers={  # mutable-ok: the exporter copies these into its session headers
             "Authorization": "Basic " + encoded_auth,
             "x-langfuse-sdk-name": "python",
-            "x-langfuse-sdk-version": langfuse_version,
+            "x-langfuse-sdk-version": version("langfuse"),
             "x-langfuse-public-key": str(public_key),
         },
         certificate_file=ca_bundle,

tests/test_litellm/integrations/langfuse/test_langfuse_sdk.py

@@ -941,6 +941,7 @@ def test_ssl_exporter_is_only_built_with_custom_tls_material(monkeypatch, tmp_pa
     assert exporter._endpoint == "https://lf.internal.example/api/public/otel/v1/traces"
     assert exporter._certificate_file == str(ca_path)
     assert exporter._headers["x-langfuse-public-key"] == "pk"
+    assert exporter._headers["x-langfuse-sdk-version"] == installed_langfuse_version()
 
 
 def test_second_client_on_the_same_key_does_not_build_another_provider():