fix(drop_params): honor string values in litellm_params and the LITELLM_DROP_PARAMS env var

get_litellm_params normalizes drop_params once, so a client-body string and
router_settings.default_litellm_params reach the anthropic, bedrock, and
azure_ai gates as a bool. LITELLM_DROP_PARAMS=false now means off. A value
that is neither a flag nor a string logs one warning and counts as unset,
both in the deployment validator and in litellm_settings.

litellm/__init__.py

@@ -47,6 +47,7 @@ from typing import (
 )
 from litellm.types.integrations.datadog import DatadogInitParams
 from litellm.types.integrations.newrelic import NewRelicInitParams
+from litellm.litellm_core_utils.core_helpers import normalize_drop_params
 from litellm._logging import (
     set_verbose,
     _turn_on_debug,
@@ -238,7 +239,7 @@ token: Optional[str] = (
 )
 telemetry = True
 max_tokens: int = DEFAULT_MAX_TOKENS  # OpenAI Defaults
-drop_params = bool(os.getenv("LITELLM_DROP_PARAMS", False))
+drop_params = bool(normalize_drop_params(os.getenv("LITELLM_DROP_PARAMS")))
 modify_params = bool(os.getenv("LITELLM_MODIFY_PARAMS", False))
 use_chat_completions_url_for_anthropic_messages: bool = bool(
     os.getenv("LITELLM_USE_CHAT_COMPLETIONS_URL_FOR_ANTHROPIC_MESSAGES", False)

litellm/litellm_core_utils/core_helpers.py

@@ -42,7 +42,7 @@ _DROP_PARAMS_BOOL: Final = TypeAdapter(bool)
 
 
 def normalize_drop_params(value: object) -> bool | None:
-    if isinstance(value, bool):
+    if value is None or isinstance(value, bool):
         return value
     try:
         return _DROP_PARAMS_BOOL.validate_python(value.strip() if isinstance(value, str) else value)

litellm/litellm_core_utils/get_litellm_params.py

@@ -2,6 +2,7 @@ from collections.abc import Mapping, MutableMapping
 from types import MappingProxyType
 from typing import Final
 
+from litellm.litellm_core_utils.core_helpers import normalize_drop_params
 from litellm.llms.openai.data_residency import infer_openai_data_residency
 
 AWS_CREDENTIAL_KWARGS_KEYS: Final = frozenset(
@@ -113,7 +114,7 @@ def get_litellm_params(
     custom_prompt_dict: dict | None = None,
     litellm_metadata: dict | None = None,
     disable_add_transform_inline_image_block: bool | None = None,
-    drop_params: bool | None = None,
+    drop_params: bool | str | None = None,
     prompt_id: str | None = None,
     prompt_variables: dict | None = None,
     async_call: bool | None = None,
@@ -175,7 +176,7 @@ def get_litellm_params(
         "custom_prompt_dict": custom_prompt_dict,
         "litellm_metadata": litellm_metadata,
         "disable_add_transform_inline_image_block": disable_add_transform_inline_image_block,
-        "drop_params": drop_params,
+        "drop_params": normalize_drop_params(drop_params),
         "prompt_id": prompt_id,
         "prompt_variables": prompt_variables,
         "async_call": async_call,

litellm/proxy/proxy_server.py

@@ -5510,7 +5510,7 @@ class ProxyConfig:
                     parse_budget_reset_time(value)
                     setattr(litellm, key, value)
                 elif key == "drop_params":
-                    litellm.drop_params = bool(normalize_drop_params(value))
+                    litellm.drop_params = _drop_params_from_litellm_settings(value)
                 else:
                     verbose_proxy_logger.debug(
                         "%s setting litellm.%s=%s%s",
@@ -16915,6 +16915,13 @@ def _redact_config_param_value_for_logging(param_name: str | None, param_value:
     return param_value
 
 
+def _drop_params_from_litellm_settings(value: object) -> bool:
+    normalized: Final = normalize_drop_params(value)
+    if normalized is None and value is not None:
+        verbose_proxy_logger.warning("litellm_settings.drop_params=%r is not a flag value, treating it as off", value)
+    return bool(normalized)
+
+
 def _redact_general_setting_value(field_name: str, value: JsonValue, is_full_admin: bool) -> JsonValue:
     if is_full_admin:
         return value

litellm/types/router.py

@@ -12,6 +12,7 @@ import httpx
 from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator
 from typing_extensions import Protocol, ReadOnly, Required, TypedDict, runtime_checkable
 
+from litellm._logging import verbose_logger
 from litellm._uuid import uuid
 from litellm.litellm_core_utils.core_helpers import normalize_drop_params
 
@@ -412,7 +413,11 @@ class GenericLiteLLMParams(CredentialLiteLLMParams, CustomPricingLiteLLMParams):
         normalized: Final = normalize_drop_params(value)
         if normalized is not None:
             return normalized
-        return value if isinstance(value, str) else None
+        if isinstance(value, str):
+            return value
+        if value is not None:
+            verbose_logger.warning("drop_params=%r is not a flag value, treating it as unset", value)
+        return None
 
     def __contains__(self, key) -> bool:
         # Define custom behavior for the 'in' operator

tests/test_litellm/litellm_core_utils/test_get_litellm_params.py

@@ -215,3 +215,11 @@ class TestMetadataFallsBackToLitellmMetadata:
         assert result["metadata"] is not litellm_metadata
         result["metadata"].pop("trace_id")
         assert litellm_metadata == {"trace_id": "trace-1"}
+
+
+@pytest.mark.parametrize(
+    "value, expected",
+    [("true", True), ("false", False), (" TRUE ", True), (True, True), (None, None), ("os.environ/DROP_PARAMS", None)],
+)
+def test_drop_params_strings_reach_litellm_params_as_flags(value, expected):
+    assert get_litellm_params(drop_params=value)["drop_params"] is expected

tests/test_litellm/proxy/proxy_server/test_proxy_config.py

@@ -9,6 +9,7 @@ Pins covered:
 from __future__ import annotations
 
 import json
+import logging
 import os
 import re
 from types import SimpleNamespace
@@ -2474,6 +2475,39 @@ async def test_ProxyConfig_load_config_turns_litellm_settings_drop_params_string
     assert litellm.drop_params is expected
 
 
+@pytest.mark.asyncio
+async def test_ProxyConfig_load_config_resolves_a_litellm_settings_drop_params_env_ref(tmp_path, monkeypatch):
+    f = tmp_path / "c.yaml"
+    f.write_text("model_list: []\nlitellm_settings:\n  drop_params: os.environ/DROP_PARAMS_FROM_ENV\n")
+    monkeypatch.setattr("litellm.proxy.proxy_server.prisma_client", None)
+    monkeypatch.setattr("litellm.proxy.proxy_server.store_model_in_db", False)
+    monkeypatch.delenv("LITELLM_CONFIG_BUCKET_NAME", raising=False)
+    monkeypatch.setenv("DROP_PARAMS_FROM_ENV", "true")
+    monkeypatch.setattr(litellm, "drop_params", False)
+
+    await ProxyConfig().load_config(router=None, config_file_path=str(f))
+
+    assert litellm.drop_params is True
+
+
+@pytest.mark.asyncio
+async def test_ProxyConfig_load_config_warns_and_turns_off_a_non_flag_litellm_settings_drop_params(
+    tmp_path, monkeypatch, caplog
+):
+    f = tmp_path / "c.yaml"
+    f.write_text("model_list: []\nlitellm_settings:\n  drop_params: ture\n")
+    monkeypatch.setattr("litellm.proxy.proxy_server.prisma_client", None)
+    monkeypatch.setattr("litellm.proxy.proxy_server.store_model_in_db", False)
+    monkeypatch.delenv("LITELLM_CONFIG_BUCKET_NAME", raising=False)
+    monkeypatch.setattr(litellm, "drop_params", True)
+
+    with caplog.at_level(logging.WARNING, logger="LiteLLM Proxy"):
+        await ProxyConfig().load_config(router=None, config_file_path=str(f))
+
+    assert litellm.drop_params is False
+    assert "litellm_settings.drop_params='ture' is not a flag value, treating it as off" in caplog.text
+
+
 # ---------------------------------------------------------------------------
 # ProxyConfig.decrypt_model_list_from_db
 # ---------------------------------------------------------------------------

tests/test_litellm/test_drop_params_env_var.py

@@ -0,0 +1,17 @@
+import os
+import subprocess
+import sys
+
+import pytest
+
+
+@pytest.mark.parametrize("configured, expected", [("false", "False"), ("true", "True")])
+def test_litellm_drop_params_env_var_is_parsed_as_a_flag(configured, expected):
+    result = subprocess.run(
+        [sys.executable, "-c", "import litellm; print(litellm.drop_params)"],
+        env={**os.environ, "LITELLM_DROP_PARAMS": configured},
+        capture_output=True,
+        text=True,
+        check=True,
+    )
+    assert result.stdout.strip() == expected

tests/test_litellm/types/test_router.py

@@ -1,3 +1,5 @@
+import logging
+
 import pytest
 
 from litellm.types.router import (
@@ -109,5 +111,14 @@ def test_drop_params_coerces_flags_and_keeps_unresolved_strings(value, expected)
 
 
 @pytest.mark.parametrize("value", [2, 2.5, [], {}])
-def test_drop_params_ignores_non_flag_non_string_values(value):
-    assert GenericLiteLLMParams(drop_params=value).drop_params is None
+def test_drop_params_ignores_non_flag_non_string_values_with_a_warning(value, caplog):
+    with caplog.at_level(logging.WARNING, logger="LiteLLM"):
+        assert GenericLiteLLMParams(drop_params=value).drop_params is None
+    assert f"drop_params={value!r} is not a flag value" in caplog.text
+
+
+@pytest.mark.parametrize("value", [True, "true", None, "os.environ/DROP_PARAMS", "v2:gcm:ciphertext-from-a-pre-fix-row"])
+def test_drop_params_flags_and_strings_log_nothing(value, caplog):
+    with caplog.at_level(logging.WARNING, logger="LiteLLM"):
+        GenericLiteLLMParams(drop_params=value)
+    assert caplog.text == ""