fix(init): keep non-flag LITELLM_DROP_PARAMS values on with a warning

The merge base read the variable by truthiness, so any non-empty value
turned the global flag on. Parsing it as a flag made a value such as
temperature or enabled silently turn it off, and the only docs for the
variable describe it as a list of parameter names, so keep those values
on and log a warning that asks for true or false. A blank value stays off
without a warning

litellm/__init__.py

@@ -47,7 +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 drop_params_flag
+from litellm.litellm_core_utils.core_helpers import drop_params_env_flag
 from litellm._logging import (
     set_verbose,
     _turn_on_debug,
@@ -239,7 +239,7 @@ token: Optional[str] = (
 )
 telemetry = True
 max_tokens: int = DEFAULT_MAX_TOKENS  # OpenAI Defaults
-drop_params = drop_params_flag(os.getenv("LITELLM_DROP_PARAMS"), "LITELLM_DROP_PARAMS", verbose_logger)
+drop_params = drop_params_env_flag(os.environ, verbose_logger)
 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

@@ -58,6 +58,22 @@ def drop_params_flag(value: object, source: str, logger: logging.Logger) -> bool
     return bool(normalized)
 
 
+DROP_PARAMS_ENV_VAR: Final = "LITELLM_DROP_PARAMS"
+
+
+def drop_params_env_flag(environ: Mapping[str, str], logger: logging.Logger) -> bool:
+    configured: Final = environ.get(DROP_PARAMS_ENV_VAR, "").strip()
+    if configured == "":
+        return False
+    normalized: Final = normalize_drop_params(configured)
+    if normalized is None:
+        logger.warning(
+            "%s=%r is not a flag value, treating it as on. Set it to true or false", DROP_PARAMS_ENV_VAR, configured
+        )
+        return True
+    return normalized
+
+
 def safe_divide(
     numerator: float,
     denominator: float,

tests/test_litellm/litellm_core_utils/test_core_helpers.py

@@ -6,6 +6,7 @@ import pytest
 
 from litellm.litellm_core_utils.core_helpers import (
     _FINISH_REASON_MAP,
+    drop_params_env_flag,
     drop_params_flag,
     get_or_create_metadata_bucket,
     map_finish_reason,
@@ -301,6 +302,33 @@ def test_drop_params_flag_treats_non_flag_values_as_off_with_a_warning(value, ca
     assert f"LITELLM_DROP_PARAMS={value!r} is not a flag value, treating it as off" in caplog.text
 
 
+@pytest.mark.parametrize(
+    "environ, expected",
+    [
+        ({}, False),
+        ({"LITELLM_DROP_PARAMS": ""}, False),
+        ({"LITELLM_DROP_PARAMS": "   "}, False),
+        ({"LITELLM_DROP_PARAMS": "true"}, True),
+        ({"LITELLM_DROP_PARAMS": " False "}, False),
+        ({"LITELLM_DROP_PARAMS": "0"}, False),
+    ],
+)
+def test_drop_params_env_flag_reads_a_flag_without_a_warning(environ, expected, caplog):
+    with caplog.at_level(logging.WARNING, logger="drop-params-test"):
+        assert drop_params_env_flag(environ, logging.getLogger("drop-params-test")) is expected
+    assert caplog.text == ""
+
+
+@pytest.mark.parametrize("configured", ["temperature", "temperature,top_p", "enabled"])
+def test_drop_params_env_flag_keeps_a_non_flag_value_on_with_a_warning(configured, caplog):
+    with caplog.at_level(logging.WARNING, logger="drop-params-test"):
+        assert drop_params_env_flag({"LITELLM_DROP_PARAMS": configured}, logging.getLogger("drop-params-test")) is True
+    assert (
+        f"LITELLM_DROP_PARAMS={configured!r} is not a flag value, treating it as on. Set it to true or false"
+        in caplog.text
+    )
+
+
 class TestIsExpectedClientError:
     def test_status_ranges(self):
         from litellm.litellm_core_utils.core_helpers import is_expected_client_error

tests/test_litellm/test_drop_params_env_var.py

@@ -15,7 +15,7 @@ def _import_litellm_with(configured: str) -> subprocess.CompletedProcess[str]:
     )
 
 
-@pytest.mark.parametrize("configured, expected", [("false", "False"), ("true", "True")])
+@pytest.mark.parametrize("configured, expected", [("false", "False"), ("true", "True"), ("", "False")])
 def test_litellm_drop_params_env_var_is_parsed_as_a_flag(configured, expected):
     result = _import_litellm_with(configured)
 
@@ -23,8 +23,11 @@ def test_litellm_drop_params_env_var_is_parsed_as_a_flag(configured, expected):
     assert "is not a flag value" not in result.stderr
 
 
-def test_litellm_drop_params_env_var_non_flag_value_is_off_with_a_warning():
+def test_litellm_drop_params_env_var_non_flag_value_stays_on_with_a_warning():
     result = _import_litellm_with("temperature")
 
-    assert result.stdout.strip() == "False"
-    assert "LITELLM_DROP_PARAMS='temperature' is not a flag value, treating it as off" in result.stderr
+    assert result.stdout.strip() == "True"
+    assert (
+        "LITELLM_DROP_PARAMS='temperature' is not a flag value, treating it as on. Set it to true or false"
+        in result.stderr
+    )