safety API cleanup part 1

Sample adapter implementation for Bedrock implementation of Guardrails

llama_stack/providers/impls/meta_reference/safety/safety.py

@@ -23,13 +23,6 @@ from .shields import (
 )
 
 
-def resolve_and_get_path(model_name: str) -> str:
-    model = resolve_model(model_name)
-    assert model is not None, f"Could not resolve model {model_name}"
-    model_dir = model_local_dir(model.descriptor())
-    return model_dir
-
-
 class MetaReferenceSafetyImpl(Safety):
     def __init__(self, config: SafetyConfig) -> None:
         self.config = config
@@ -50,16 +43,17 @@ class MetaReferenceSafetyImpl(Safety):
             model_dir = resolve_and_get_path(shield_cfg.model)
             _ = PromptGuardShield.instance(model_dir)
 
-    async def run_shields(
+    async def run_shield(
         self,
+        shield_type: ShieldType,
         messages: List[Message],
-        shields: List[ShieldDefinition],
     ) -> RunShieldResponse:
-        shields = [shield_config_to_shield(c, self.config) for c in shields]
+        assert shield_type in [
+            "llama_guard",
+            "prompt_guard",
+        ], f"Unknown shield {shield_type}"
 
-        responses = await asyncio.gather(*[shield.run(messages) for shield in shields])
-
-        return RunShieldResponse(responses=responses)
+        raise NotImplementedError()
 
 
 def shield_type_equals(a: ShieldType, b: ShieldType):