fix(guardrails): treat an unknown straiker api_version as unset instead of skipping the guardrail (#43956)

The integration test hunks are dropped because tests/integration/observability/test_straiker_v3_platform.py is not on this line

(cherry picked from commit a3a7650569)

litellm/proxy/guardrails/guardrail_hooks/straiker/__init__.py

@@ -1,8 +1,9 @@
 from typing import TYPE_CHECKING, Final, Literal
 
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
 
 import litellm
+from litellm._logging import verbose_proxy_logger
 from litellm.types.guardrails import SupportedGuardrailIntegrations
 
 from .straiker import StraikerGuardrail
@@ -17,6 +18,18 @@ class _V3Routing(BaseModel):
     client: str | None = None
     format_hint: Literal["anthropic.messages", "openai.chat"] | None = None
 
+    @field_validator("api_version", mode="before")
+    @classmethod
+    def _unknown_api_version_is_unset(cls, value: object) -> object:
+        if value is None or value in ("v1", "v3"):
+            return value
+        verbose_proxy_logger.warning(
+            "Straiker guardrail: ignoring api_version %r, expected 'v1', 'v3' or unset; "
+            "the route follows the api_key prefix",
+            value,
+        )
+        return None
+
 
 _OPTIONAL_INIT_FIELDS: Final = (
     "timeout",

tests/test_litellm/proxy/guardrails/guardrail_hooks/test_straiker.py

@@ -1,6 +1,6 @@
 import json
 from types import SimpleNamespace
-from unittest.mock import AsyncMock, MagicMock
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import httpx
 import pytest
@@ -1216,6 +1216,58 @@ def test_v3_initializer_reads_api_version_from_config():
     assert g._webhook_url().endswith("/api/v3/detect")
 
 
+@pytest.mark.parametrize("api_version", ["2024-09-01", "", "v2"])
+@pytest.mark.parametrize(("api_key", "expected"), [("c4ac433a-uuid", "v1"), (V3_KEY, "v3")])
+def test_unknown_api_version_follows_key_prefix(api_version, api_key, expected, monkeypatch):
+    import litellm
+    from litellm._logging import verbose_proxy_logger
+    from litellm.types.guardrails import Guardrail, LitellmParams
+
+    monkeypatch.setattr(litellm, "callbacks", litellm.callbacks.copy())
+
+    with patch.object(verbose_proxy_logger, "warning") as warning:
+        g = initialize_guardrail(
+            LitellmParams(guardrail="straiker", mode="pre_call", api_key=api_key, api_version=api_version),
+            Guardrail(guardrail_name="straiker", litellm_params={"guardrail": "straiker", "mode": "pre_call"}),
+        )
+
+    assert g.api_version == expected
+    expected_path = "/api/v3/detect" if expected == "v3" else "/api/v1/detect/webhook"
+    assert g._webhook_url().endswith(expected_path)
+    warning.assert_called_once()
+    assert warning.call_args.args[-1] == api_version
+
+
+def test_init_guardrails_v2_registers_straiker_with_unknown_api_version(monkeypatch):
+    import litellm
+    from litellm.proxy.guardrails import guardrail_registry
+    from litellm.proxy.guardrails.guardrail_registry import InMemoryGuardrailHandler
+    from litellm.proxy.guardrails.init_guardrails import init_guardrails_v2
+
+    handler = InMemoryGuardrailHandler()
+    monkeypatch.setattr(guardrail_registry, "IN_MEMORY_GUARDRAIL_HANDLER", handler)
+    monkeypatch.setattr(litellm, "callbacks", litellm.callbacks.copy())
+
+    init_guardrails_v2(
+        all_guardrails=[
+            {
+                "guardrail_name": "straiker-unknown-version",
+                "litellm_params": {
+                    "guardrail": "straiker",
+                    "mode": "pre_call",
+                    "api_key": V3_KEY,
+                    "api_version": "2024-09-01",
+                },
+            }
+        ]
+    )
+
+    callbacks = tuple(handler.guardrail_id_to_custom_guardrail.values())
+    assert len(callbacks) == 1
+    assert isinstance(callbacks[0], StraikerGuardrail)
+    assert callbacks[0].api_version == "v3"
+
+
 @pytest.mark.asyncio
 async def test_v3_request_phase_relays_the_provider_body_and_nothing_else():
     g = _make_guardrail(api_key=V3_KEY, source="Yum Gateway")