Merge pull request #18775 from BerriAI/litellm_fs_callback_fix

[Fix] Normalize Proxy Config Callback

litellm/proxy/proxy_server.py

@@ -3402,8 +3402,8 @@ class ProxyConfig:
 
         def _deep_merge_dicts(dst: dict, src: dict) -> None:
             """
-            Deep-merge src into dst, skipping None values from src.
-            On conflicts, src (DB) wins.
+            Deep-merge src into dst, skipping None values and empty lists from src.
+            On conflicts, src (DB) wins, but empty lists are treated as "no value" and don't overwrite.
             """
             stack = [(dst, src)]
             while stack:
@@ -3412,6 +3412,9 @@ class ProxyConfig:
                     if v is None:
                         # Preserve existing config when DB value is None (matches prior behavior)
                         continue
+                    # Skip empty lists - treat them as "no value" to preserve file config
+                    if isinstance(v, list) and len(v) == 0:
+                        continue
                     if isinstance(v, dict) and isinstance(d.get(k), dict):
                         stack.append((d[k], v))
                     else:
@@ -9762,6 +9765,18 @@ async def get_config():  # noqa: PLR0915
         _failure_callbacks = _litellm_settings.get("failure_callback", [])
         _success_and_failure_callbacks = _litellm_settings.get("callbacks", [])
 
+        # Normalize string callbacks to lists
+        def normalize_callback(callback):
+            if isinstance(callback, str):
+                return [callback]
+            elif callback is None:
+                return []
+            return callback
+
+        _success_callbacks = normalize_callback(_success_callbacks)
+        _failure_callbacks = normalize_callback(_failure_callbacks)
+        _success_and_failure_callbacks = normalize_callback(_success_and_failure_callbacks)
+
         _data_to_return = []
         """
         [

tests/test_litellm/proxy/test_proxy_server.py

@@ -3036,3 +3036,91 @@ def test_get_image_root_case_uses_current_dir(monkeypatch):
 
         # Verify FileResponse was called
         assert mock_file_response.called, "FileResponse should be called"
+
+
+def test_get_config_normalizes_string_callbacks(monkeypatch):
+    """
+    Test that /get/config/callbacks normalizes string callbacks to lists.
+    """
+    from litellm.proxy.proxy_server import app, proxy_config, user_api_key_auth
+
+    config_data = {
+        "litellm_settings": {
+            "success_callback": "langfuse",
+            "failure_callback": None,
+            "callbacks": ["prometheus", "datadog"],
+        },
+        "general_settings": {},
+        "environment_variables": {},
+    }
+
+    mock_router = MagicMock()
+    mock_router.get_settings.return_value = {}
+    monkeypatch.setattr("litellm.proxy.proxy_server.llm_router", mock_router)
+    monkeypatch.setattr(
+        proxy_config, "get_config", AsyncMock(return_value=config_data)
+    )
+
+    original_overrides = app.dependency_overrides.copy()
+    app.dependency_overrides[user_api_key_auth] = lambda: MagicMock()
+
+    client = TestClient(app)
+    try:
+        response = client.get("/get/config/callbacks")
+    finally:
+        app.dependency_overrides = original_overrides
+
+    assert response.status_code == 200
+    callbacks = response.json()["callbacks"]
+
+    success_callbacks = [cb["name"] for cb in callbacks if cb.get("type") == "success"]
+    failure_callbacks = [cb["name"] for cb in callbacks if cb.get("type") == "failure"]
+    success_and_failure_callbacks = [
+        cb["name"] for cb in callbacks if cb.get("type") == "success_and_failure"
+    ]
+
+    assert "langfuse" in success_callbacks
+    assert len(failure_callbacks) == 0
+    assert "prometheus" in success_and_failure_callbacks
+    assert "datadog" in success_and_failure_callbacks
+
+
+def test_deep_merge_dicts_skips_none_and_empty_lists(monkeypatch):
+    """
+    Test that _update_config_fields deep merge skips None values and empty lists.
+    """
+    from litellm.proxy.proxy_server import ProxyConfig
+
+    proxy_config = ProxyConfig()
+
+    current_config = {
+        "general_settings": {
+            "max_parallel_requests": 10,
+            "allowed_models": ["gpt-3.5-turbo", "gpt-4"],
+            "nested": {
+                "key1": "value1",
+                "key2": "value2",
+            },
+        }
+    }
+
+    db_param_value = {
+        "max_parallel_requests": None,
+        "allowed_models": [],
+        "new_key": "new_value",
+        "nested": {
+            "key1": "updated_value1",
+            "key3": "value3",
+        },
+    }
+
+    result = proxy_config._update_config_fields(
+        current_config, "general_settings", db_param_value
+    )
+
+    assert result["general_settings"]["max_parallel_requests"] == 10
+    assert result["general_settings"]["allowed_models"] == ["gpt-3.5-turbo", "gpt-4"]
+    assert result["general_settings"]["new_key"] == "new_value"
+    assert result["general_settings"]["nested"]["key1"] == "updated_value1"
+    assert result["general_settings"]["nested"]["key2"] == "value2"
+    assert result["general_settings"]["nested"]["key3"] == "value3"