fix(logging): parse JSON_LOGS env var so JSON_LOGS=False disables JSON logs

json_logs was derived with bool(os.getenv("JSON_LOGS", False)). os.getenv
returns a string (or None), never the bool default, so bool() is truthy for
every non-empty value including "False", "0", and "no". Once a user followed
the docs and set JSON_LOGS to enable it, there was no value (other than empty
string) that would turn it back off, and the flag also propagates to
litellm.json_logs which litellm-proxy-extras reads, corrupting its formatting
too.

Parse it case-insensitively so only "true" enables JSON logging, matching the
existing litellm_proxy_extras/_logging.py fallback. The parse is extracted into
a small pure helper so it is unit-testable without import-time side effects, and
inlining avoids a circular import with str_to_bool in secret_managers.main
(which imports from this module).

litellm/_logging.py

@@ -77,7 +77,11 @@ class SecretRedactionFilter(logging.Filter):
 _secret_filter = SecretRedactionFilter()
 
 
-json_logs = bool(os.getenv("JSON_LOGS", False))
+def _env_flag_enabled(value: Optional[str]) -> bool:
+    return (value or "").strip().lower() == "true"
+
+
+json_logs = _env_flag_enabled(os.getenv("JSON_LOGS"))
 # Create a handler for the logger (you may need to adapt this based on your needs)
 log_level = os.getenv("LITELLM_LOG", "DEBUG")
 numeric_level: str = getattr(logging, log_level.upper())

tests/test_litellm/test_logging.py

@@ -16,6 +16,7 @@ import litellm
 from litellm._logging import (
     ALL_LOGGERS,
     JsonFormatter,
+    _env_flag_enabled,
     _initialize_loggers_with_handler,
     _turn_on_json,
     verbose_logger,
@@ -66,6 +67,33 @@ def test_json_mode_emits_one_record_per_logger(capfd):
         assert "timestamp" in obj, "`timestamp` key missing"
 
 
+@pytest.mark.parametrize(
+    "value, expected",
+    [
+        ("True", True),
+        ("true", True),
+        ("TRUE", True),
+        (" true ", True),
+        ("1", False),
+        ("False", False),
+        ("false", False),
+        ("0", False),
+        ("no", False),
+        ("off", False),
+        ("", False),
+        (None, False),
+    ],
+)
+def test_env_flag_enabled_only_true_enables(value, expected):
+    """
+    Regression: JSON_LOGS is a boolean env flag, so only "true" (case-insensitive)
+    may enable it. The previous bool(os.getenv("JSON_LOGS", False)) turned any
+    non-empty string, including "False"/"0"/"no", into True, so JSON logging could
+    never be disabled via the documented env var.
+    """
+    assert _env_flag_enabled(value) is expected
+
+
 def test_json_formatter_parses_embedded_json_message():
     """
     Test that JsonFormatter parses embedded JSON in the message field and promotes