feat: implement dynamic model detection support for inference providers using litellm

llama_stack/providers/utils/inference/litellm_openai_mixin.py

@@ -73,6 +73,15 @@ def __init__(
         provider_data_api_key_field: str,
         openai_compat_api_base: str | None = None,
     ):
+        """
+        Initialize the LiteLLMOpenAIMixin.
+
+        :param model_entries: The model entries to register.
+        :param api_key_from_config: The API key to use from the config.
+        :param provider_data_api_key_field: The field in the provider data that contains the API key.
+        :param litellm_provider_name: The name of the provider, used for model lookups.
+        :param openai_compat_api_base: The base URL for OpenAI compatibility, or None if not using OpenAI compatibility.
+        """
         ModelRegistryHelper.__init__(self, model_entries)
 
         self.litellm_provider_name = litellm_provider_name
@@ -428,3 +437,17 @@ async def batch_chat_completion(
         logprobs: LogProbConfig | None = None,
     ):
         raise NotImplementedError("Batch chat completion is not supported for OpenAI Compat")
+
+    async def check_model_availability(self, model: str) -> bool:
+        """
+        Check if a specific model is available via LiteLLM for the current
+        provider (self.litellm_provider_name).
+
+        :param model: The model identifier to check.
+        :return: True if the model is available dynamically, False otherwise.
+        """
+        if self.litellm_provider_name not in litellm.models_by_provider:
+            logger.error(f"Provider {self.litellm_provider_name} is not registered in litellm.")
+            return False
+
+        return model in litellm.models_by_provider[self.litellm_provider_name]