From 13d12ae4b841e25a0368e9d0ea58ce03957fd99a Mon Sep 17 00:00:00 2001
From: yucheng <yucheng@berri.ai>
Date: Thu, 17 Sep 2026 03:23:10 +0000
Subject: [PATCH] fix(langfuse): warn about ignored UPSTREAM_LANGFUSE_* on the
 shared client init path too

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 litellm/integrations/langfuse/langfuse.py     | 14 +++++++++----
 .../langfuse/langfuse_prompt_management.py    |  2 ++
 .../test_langfuse_prompt_management.py        | 20 +++++++++++++++++++
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/litellm/integrations/langfuse/langfuse.py b/litellm/integrations/langfuse/langfuse.py
index 2311575c023..4b55c1eef76 100644
--- a/litellm/integrations/langfuse/langfuse.py
+++ b/litellm/integrations/langfuse/langfuse.py
@@ -307,6 +307,15 @@ def resolve_langfuse_credentials(
     return public_key, secret_key, resolved_host
 
 
+def warn_if_upstream_langfuse_configured() -> None:
+    if os.getenv("UPSTREAM_LANGFUSE_SECRET_KEY") is None:
+        return
+    verbose_logger.warning(
+        "UPSTREAM_LANGFUSE_* is no longer supported: the langfuse callback moved to SDK v4, "
+        "which has no second ingestion client. The values are ignored."
+    )
+
+
 def parse_langfuse_debug(raw_value: str | None) -> bool:
     """Parse the LANGFUSE_DEBUG value into the boolean flag the langfuse client expects."""
     return raw_value is not None and raw_value.strip().lower() in ("true", "1")
@@ -393,11 +402,8 @@ class LangFuseLogger:
             except Exception:
                 verbose_logger.debug("Langfuse project id unavailable, alerting links will omit it")
 
+        warn_if_upstream_langfuse_configured()
         if os.getenv("UPSTREAM_LANGFUSE_SECRET_KEY") is not None:
-            verbose_logger.warning(
-                "UPSTREAM_LANGFUSE_* is no longer supported: the langfuse callback moved to SDK v4, "
-                "which has no second ingestion client. The values are ignored."
-            )
             self.upstream_langfuse_secret_key = os.getenv("UPSTREAM_LANGFUSE_SECRET_KEY")
             self.upstream_langfuse_public_key = os.getenv("UPSTREAM_LANGFUSE_PUBLIC_KEY")
             self.upstream_langfuse_host = os.getenv("UPSTREAM_LANGFUSE_HOST")
diff --git a/litellm/integrations/langfuse/langfuse_prompt_management.py b/litellm/integrations/langfuse/langfuse_prompt_management.py
index d8b3689eb0a..9982f48616a 100644
--- a/litellm/integrations/langfuse/langfuse_prompt_management.py
+++ b/litellm/integrations/langfuse/langfuse_prompt_management.py
@@ -25,6 +25,7 @@ from .langfuse import (
     parse_langfuse_debug,
     raise_if_unsupported_langfuse_version,
     resolve_langfuse_credentials,
+    warn_if_upstream_langfuse_configured,
 )
 from .langfuse_handler import LangFuseHandler
 from .langfuse_mock_client import create_mock_langfuse_client, should_use_langfuse_mock
@@ -103,6 +104,7 @@ def langfuse_client_init(
     }
 
     raise_if_unsupported_langfuse_version(installed_langfuse_version())
+    warn_if_upstream_langfuse_configured()
 
     import httpx
 
diff --git a/tests/test_litellm/integrations/langfuse/test_langfuse_prompt_management.py b/tests/test_litellm/integrations/langfuse/test_langfuse_prompt_management.py
index b1997b654ac..f7c09e4ad1e 100644
--- a/tests/test_litellm/integrations/langfuse/test_langfuse_prompt_management.py
+++ b/tests/test_litellm/integrations/langfuse/test_langfuse_prompt_management.py
@@ -134,6 +134,26 @@ def test_langfuse_client_init_resolves_deployment_environment(monkeypatch, env_v
     assert _RecordingLangfuseForEnv.last_environment == expected
 
 
+def test_langfuse_client_init_warns_that_upstream_langfuse_is_ignored(monkeypatch, caplog):
+    """The YAML `callbacks: ["langfuse"]` path builds its client here, not through LangFuseLogger.__init__,
+    so an operator who still sets UPSTREAM_LANGFUSE_* must get the same startup warning on this path."""
+    monkeypatch.setenv("LANGFUSE_PUBLIC_KEY", "pk-test")
+    monkeypatch.setenv("LANGFUSE_SECRET_KEY", "sk-test")
+    monkeypatch.setenv("LANGFUSE_HOST", "https://test.langfuse.com")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_SECRET_KEY", "sk-upstream")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_HOST", "https://upstream.example")
+    with (
+        patch(
+            "litellm.integrations.langfuse.langfuse_sdk.Langfuse", _RecordingLangfuseForEnv
+        ),  # test-quality-ok: the ctor must be intercepted where acquire_langfuse_client resolves it; a real client spawns export threads
+        caplog.at_level("WARNING", logger="LiteLLM"),
+    ):
+        langfuse_client_init.cache_clear()
+        langfuse_client_init()
+    langfuse_client_init.cache_clear()
+    assert any("UPSTREAM_LANGFUSE_* is no longer supported" in record.getMessage() for record in caplog.records)
+
+
 def test_langfuse_client_init_mock_mode_makes_no_network_calls(monkeypatch):
     """LANGFUSE_MOCK promises full execution without egress.