From ef27e618adef480104e08c83ce75593f4e10b6f3 Mon Sep 17 00:00:00 2001
From: Hassieb Pakzad <68423100+hassiebp@users.noreply.github.com>
Date: Mon, 20 Apr 2026 14:38:46 +0200
Subject: [PATCH] fix(langfuse): send v4 ingestion header for otel callback

---
 .../integrations/langfuse/langfuse_otel.py    | 25 +++++++++--
 tests/test_service_logger_otel.py             | 45 ++++++++++++++++++-
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/litellm/integrations/langfuse/langfuse_otel.py b/litellm/integrations/langfuse/langfuse_otel.py
index b96ec72b04e..276fd24cc32 100644
--- a/litellm/integrations/langfuse/langfuse_otel.py
+++ b/litellm/integrations/langfuse/langfuse_otel.py
@@ -25,6 +25,8 @@ else:
 
 LANGFUSE_CLOUD_EU_ENDPOINT = "https://cloud.langfuse.com/api/public/otel"
 LANGFUSE_CLOUD_US_ENDPOINT = "https://us.cloud.langfuse.com/api/public/otel"
+LANGFUSE_OTEL_INGESTION_VERSION_HEADER = "x-langfuse-ingestion-version"
+LANGFUSE_OTEL_INGESTION_VERSION = "4"
 
 
 class LangfuseOtelLogger(OpenTelemetry):
@@ -295,7 +297,9 @@ class LangfuseOtelLogger(OpenTelemetry):
         auth_header = LangfuseOtelLogger._get_langfuse_authorization_header(
             public_key=public_key, secret_key=secret_key
         )
-        otlp_auth_headers = f"Authorization={auth_header}"
+        otlp_auth_headers = LangfuseOtelLogger._format_otel_headers(
+            LangfuseOtelLogger._build_langfuse_otel_headers(auth_header)
+        )
 
         return OpenTelemetryConfig(
             exporter="otlp_http",
@@ -344,7 +348,9 @@ class LangfuseOtelLogger(OpenTelemetry):
         auth_header = LangfuseOtelLogger._get_langfuse_authorization_header(
             public_key=public_key, secret_key=secret_key
         )
-        otlp_auth_headers = f"Authorization={auth_header}"
+        otlp_auth_headers = LangfuseOtelLogger._format_otel_headers(
+            LangfuseOtelLogger._build_langfuse_otel_headers(auth_header)
+        )
 
         # Prevent modification of global env vars which causes leakage
         # os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = endpoint
@@ -365,6 +371,17 @@ class LangfuseOtelLogger(OpenTelemetry):
         auth_header = base64.b64encode(auth_string.encode()).decode()
         return f"Basic {auth_header}"
 
+    @staticmethod
+    def _build_langfuse_otel_headers(auth_header: str) -> dict[str, str]:
+        return {
+            "Authorization": auth_header,
+            LANGFUSE_OTEL_INGESTION_VERSION_HEADER: LANGFUSE_OTEL_INGESTION_VERSION,
+        }
+
+    @staticmethod
+    def _format_otel_headers(headers: dict[str, str]) -> str:
+        return ",".join(f"{key}={value}" for key, value in headers.items())
+
     def construct_dynamic_otel_headers(
         self, standard_callback_dynamic_params: StandardCallbackDynamicParams
     ) -> Optional[dict]:
@@ -389,7 +406,9 @@ class LangfuseOtelLogger(OpenTelemetry):
                 public_key=dynamic_langfuse_public_key,
                 secret_key=dynamic_langfuse_secret_key,
             )
-            dynamic_headers["Authorization"] = auth_header
+            dynamic_headers = LangfuseOtelLogger._build_langfuse_otel_headers(
+                auth_header
+            )
 
         return dynamic_headers
 
diff --git a/tests/test_service_logger_otel.py b/tests/test_service_logger_otel.py
index 35070d55546..01e918d3f42 100644
--- a/tests/test_service_logger_otel.py
+++ b/tests/test_service_logger_otel.py
@@ -8,10 +8,15 @@ from unittest.mock import patch, AsyncMock, MagicMock
 sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "../..")))
 
 import litellm
-from litellm.integrations.langfuse.langfuse_otel import LangfuseOtelLogger
+from litellm.integrations.langfuse.langfuse_otel import (
+    LANGFUSE_OTEL_INGESTION_VERSION,
+    LANGFUSE_OTEL_INGESTION_VERSION_HEADER,
+    LangfuseOtelLogger,
+)
 from litellm.integrations.opentelemetry import OpenTelemetry
 from litellm.types.services import ServiceTypes
 from litellm._service_logger import ServiceLogging
+from litellm.types.utils import StandardCallbackDynamicParams
 
 
 class TestServiceLoggerOTEL(unittest.IsolatedAsyncioTestCase):
@@ -108,6 +113,44 @@ class TestServiceLoggerOTEL(unittest.IsolatedAsyncioTestCase):
                 "Generic OTEL logger should have received the log exactly once.",
             )
 
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_tracing")
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_metrics")
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_logs")
+    async def test_langfuse_otel_env_config_includes_v4_ingestion_header(
+        self, mock_logs, mock_metrics, mock_tracing
+    ):
+        logger = LangfuseOtelLogger()
+
+        headers = OpenTelemetry._get_headers_dictionary(logger.config.headers)
+
+        self.assertEqual(
+            headers[LANGFUSE_OTEL_INGESTION_VERSION_HEADER],
+            LANGFUSE_OTEL_INGESTION_VERSION,
+        )
+        self.assertTrue(headers["Authorization"].startswith("Basic "))
+
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_tracing")
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_metrics")
+    @patch("litellm.integrations.opentelemetry.OpenTelemetry._init_logs")
+    async def test_langfuse_otel_dynamic_headers_include_v4_ingestion_header(
+        self, mock_logs, mock_metrics, mock_tracing
+    ):
+        logger = LangfuseOtelLogger()
+
+        headers = logger.construct_dynamic_otel_headers(
+            StandardCallbackDynamicParams(
+                langfuse_public_key="pk-lf-dynamic",
+                langfuse_secret_key="sk-lf-dynamic",
+            )
+        )
+
+        self.assertIsNotNone(headers)
+        self.assertEqual(
+            headers[LANGFUSE_OTEL_INGESTION_VERSION_HEADER],
+            LANGFUSE_OTEL_INGESTION_VERSION,
+        )
+        self.assertTrue(headers["Authorization"].startswith("Basic "))
+
 
 if __name__ == "__main__":
     unittest.main()