fix(otel): accept langfuse_base_url (v3 naming) for per-key langfuse host, fall back to langfuse_host

litellm/integrations/langfuse/langfuse_otel.py

@@ -409,12 +409,18 @@ class LangfuseOtelLogger(OpenTelemetry):
         Per-key Langfuse credentials are only valid against the host that issued
         them, so the host must travel with the credentials. Returns None when no
         per-key host is set, falling back to the env-configured endpoint.
+
+        Prefers ``langfuse_base_url`` (the Langfuse v3 naming) and falls back to
+        the deprecated ``langfuse_host`` for backward compatibility, mirroring the
+        SDK's own ``base_url`` -> ``host`` resolution order.
         """
-        dynamic_langfuse_host = standard_callback_dynamic_params.get("langfuse_host")
-        if not dynamic_langfuse_host:
+        dynamic_langfuse_base_url = standard_callback_dynamic_params.get(
+            "langfuse_base_url"
+        ) or standard_callback_dynamic_params.get("langfuse_host")
+        if not dynamic_langfuse_base_url:
             return None
         return LangfuseOtelLogger._construct_langfuse_otel_endpoint(
-            dynamic_langfuse_host
+            dynamic_langfuse_base_url
         )
 
     def create_litellm_proxy_request_started_span(

litellm/litellm_core_utils/initialize_dynamic_callback_params.py

@@ -36,6 +36,7 @@ _supported_callback_params = [
     "langfuse_secret",
     "langfuse_secret_key",
     "langfuse_host",
+    "langfuse_base_url",
     "langfuse_prompt_version",
     "langsmith_api_key",
     "langsmith_project",

litellm/types/utils.py

@@ -2994,6 +2994,8 @@ class StandardCallbackDynamicParams(TypedDict, total=False):
     langfuse_secret: Optional[str]
     langfuse_secret_key: Optional[str]
     langfuse_host: Optional[str]
+    # Langfuse v3 naming for the host; preferred over langfuse_host where set
+    langfuse_base_url: Optional[str]
 
     # Langfuse prompt version
     langfuse_prompt_version: Optional[int]

tests/test_litellm/integrations/test_langfuse_otel.py

@@ -419,6 +419,31 @@ class TestLangfuseOtelIntegration:
             is None
         )
 
+    def test_construct_dynamic_otel_endpoint_with_base_url(self):
+        """Per-key langfuse_base_url (the Langfuse v3 naming) is honored."""
+        from litellm.types.utils import StandardCallbackDynamicParams
+
+        logger = LangfuseOtelLogger()
+        endpoint = logger.construct_dynamic_otel_endpoint(
+            StandardCallbackDynamicParams(
+                langfuse_base_url="https://us.cloud.langfuse.com"
+            )
+        )
+        assert endpoint == "https://us.cloud.langfuse.com/api/public/otel"
+
+    def test_construct_dynamic_otel_endpoint_base_url_preferred_over_host(self):
+        """When both are set, langfuse_base_url wins (mirrors the SDK's resolution order)."""
+        from litellm.types.utils import StandardCallbackDynamicParams
+
+        logger = LangfuseOtelLogger()
+        endpoint = logger.construct_dynamic_otel_endpoint(
+            StandardCallbackDynamicParams(
+                langfuse_base_url="https://us.cloud.langfuse.com",
+                langfuse_host="https://cloud.langfuse.com",
+            )
+        )
+        assert endpoint == "https://us.cloud.langfuse.com/api/public/otel"
+
     def test_get_langfuse_otel_config_with_otel_host_priority(self):
         """LANGFUSE_OTEL_HOST should take priority over LANGFUSE_HOST."""
         with patch.dict(