chore: create OpenAIMixin for inference providers with an OpenAI-compat API that need to implement openai_* methods (#2835)

# What does this PR do?

add an `OpenAIMixin` for use by inference providers who remote endpoints
support an OpenAI compatible API.

use is demonstrated by refactoring
- OpenAIInferenceAdapter
- NVIDIAInferenceAdapter (adds embedding support)
- LlamaCompatInferenceAdapter

## Test Plan

existing unit and integration tests

docs/source/contributing/new_api_provider.md

@@ -14,6 +14,41 @@ Here are some example PRs to help you get started:
    - [Nvidia Inference Implementation](https://github.com/meta-llama/llama-stack/pull/355)
    - [Model context protocol Tool Runtime](https://github.com/meta-llama/llama-stack/pull/665)
 
+## Inference Provider Patterns
+
+When implementing Inference providers for OpenAI-compatible APIs, Llama Stack provides several mixin classes to simplify development and ensure consistent behavior across providers.
+
+### OpenAIMixin
+
+The `OpenAIMixin` class provides direct OpenAI API functionality for providers that work with OpenAI-compatible endpoints. It includes:
+
+#### Direct API Methods
+- **`openai_completion()`**: Legacy text completion API with full parameter support
+- **`openai_chat_completion()`**: Chat completion API supporting streaming, tools, and function calling
+- **`openai_embeddings()`**: Text embeddings generation with customizable encoding and dimensions
+
+#### Model Management
+- **`check_model_availability()`**: Queries the API endpoint to verify if a model exists and is accessible
+
+#### Client Management
+- **`client` property**: Automatically creates and configures AsyncOpenAI client instances using your provider's credentials
+
+#### Required Implementation
+
+To use `OpenAIMixin`, your provider must implement these abstract methods:
+
+```python
+@abstractmethod
+def get_api_key(self) -> str:
+    """Return the API key for authentication"""
+    pass
+
+
+@abstractmethod
+def get_base_url(self) -> str:
+    """Return the OpenAI-compatible API base URL"""
+    pass
+```
 
 ## Testing the Provider
 

llama_stack/providers/remote/inference/llama_openai_compat/llama.py

@@ -5,17 +5,27 @@
 # the root directory of this source tree.
 import logging
 
-from llama_api_client import AsyncLlamaAPIClient, NotFoundError
-
 from llama_stack.providers.remote.inference.llama_openai_compat.config import LlamaCompatConfig
 from llama_stack.providers.utils.inference.litellm_openai_mixin import LiteLLMOpenAIMixin
+from llama_stack.providers.utils.inference.openai_mixin import OpenAIMixin
 
 from .models import MODEL_ENTRIES
 
 logger = logging.getLogger(__name__)
 
 
-class LlamaCompatInferenceAdapter(LiteLLMOpenAIMixin):
+class LlamaCompatInferenceAdapter(OpenAIMixin, LiteLLMOpenAIMixin):
+    """
+    Llama API Inference Adapter for Llama Stack.
+
+    Note: The inheritance order is important here. OpenAIMixin must come before
+    LiteLLMOpenAIMixin to ensure that OpenAIMixin.check_model_availability()
+    is used instead of ModelRegistryHelper.check_model_availability().
+
+    - OpenAIMixin.check_model_availability() queries the Llama API to check if a model exists
+    - ModelRegistryHelper.check_model_availability() (inherited by LiteLLMOpenAIMixin) just returns False and shows a warning
+    """
+
     _config: LlamaCompatConfig
 
     def __init__(self, config: LlamaCompatConfig):
@@ -28,32 +38,19 @@ class LlamaCompatInferenceAdapter(LiteLLMOpenAIMixin):
         )
         self.config = config
 
-    async def check_model_availability(self, model: str) -> bool:
+    # Delegate the client data handling get_api_key method to LiteLLMOpenAIMixin
+    get_api_key = LiteLLMOpenAIMixin.get_api_key
+
+    def get_base_url(self) -> str:
         """
-        Check if a specific model is available from Llama API.
+        Get the base URL for OpenAI mixin.
 
-        :param model: The model identifier to check.
+        :return: The Llama API base URL
-        :return: True if the model is available dynamically, False otherwise.
         """
-        try:
+        return self.config.openai_compat_api_base
-            llama_api_client = self._get_llama_api_client()
-            retrieved_model = await llama_api_client.models.retrieve(model)
-            logger.info(f"Model {retrieved_model.id} is available from Llama API")
-            return True
-
-        except NotFoundError:
-            logger.error(f"Model {model} is not available from Llama API")
-            return False
-
-        except Exception as e:
-            logger.error(f"Failed to check model availability from Llama API: {e}")
-            return False
 
     async def initialize(self):
         await super().initialize()
 
     async def shutdown(self):
         await super().shutdown()
-
-    def _get_llama_api_client(self) -> AsyncLlamaAPIClient:
-        return AsyncLlamaAPIClient(api_key=self.get_api_key(), base_url=self.config.openai_compat_api_base)

llama_stack/providers/remote/inference/nvidia/nvidia.py

@@ -7,9 +7,8 @@
 import logging
 import warnings
 from collections.abc import AsyncIterator
-from typing import Any
 
-from openai import APIConnectionError, AsyncOpenAI, BadRequestError, NotFoundError
+from openai import APIConnectionError, BadRequestError
 
 from llama_stack.apis.common.content_types import (
     InterleavedContent,
@@ -28,12 +27,6 @@ from llama_stack.apis.inference import (
     Inference,
     LogProbConfig,
     Message,
-    OpenAIChatCompletion,
-    OpenAIChatCompletionChunk,
-    OpenAICompletion,
-    OpenAIEmbeddingsResponse,
-    OpenAIMessageParam,
-    OpenAIResponseFormatParam,
     ResponseFormat,
     SamplingParams,
     TextTruncation,
@@ -47,8 +40,8 @@ from llama_stack.providers.utils.inference.model_registry import (
 from llama_stack.providers.utils.inference.openai_compat import (
     convert_openai_chat_completion_choice,
     convert_openai_chat_completion_stream,
-    prepare_openai_completion_params,
 )
+from llama_stack.providers.utils.inference.openai_mixin import OpenAIMixin
 from llama_stack.providers.utils.inference.prompt_adapter import content_has_media
 
 from . import NVIDIAConfig
@@ -64,7 +57,20 @@ from .utils import _is_nvidia_hosted
 logger = logging.getLogger(__name__)
 
 
-class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
+class NVIDIAInferenceAdapter(OpenAIMixin, Inference, ModelRegistryHelper):
+    """
+    NVIDIA Inference Adapter for Llama Stack.
+
+    Note: The inheritance order is important here. OpenAIMixin must come before
+    ModelRegistryHelper to ensure that OpenAIMixin.check_model_availability()
+    is used instead of ModelRegistryHelper.check_model_availability(). It also
+    must come before Inference to ensure that OpenAIMixin methods are available
+    in the Inference interface.
+
+    - OpenAIMixin.check_model_availability() queries the NVIDIA API to check if a model exists
+    - ModelRegistryHelper.check_model_availability() just returns False and shows a warning
+    """
+
     def __init__(self, config: NVIDIAConfig) -> None:
         # TODO(mf): filter by available models
         ModelRegistryHelper.__init__(self, model_entries=MODEL_ENTRIES)
@@ -88,45 +94,21 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
 
         self._config = config
 
-    async def check_model_availability(self, model: str) -> bool:
+    def get_api_key(self) -> str:
         """
-        Check if a specific model is available.
+        Get the API key for OpenAI mixin.
 
-        :param model: The model identifier to check.
+        :return: The NVIDIA API key
-        :return: True if the model is available dynamically, False otherwise.
         """
-        try:
+        return self._config.api_key.get_secret_value() if self._config.api_key else "NO KEY"
-            await self._client.models.retrieve(model)
-            return True
-        except NotFoundError:
-            logger.error(f"Model {model} is not available")
-        except Exception as e:
-            logger.error(f"Failed to check model availability: {e}")
-        return False
 
-    @property
+    def get_base_url(self) -> str:
-    def _client(self) -> AsyncOpenAI:
         """
-        Returns an OpenAI client for the configured NVIDIA API endpoint.
+        Get the base URL for OpenAI mixin.
 
-        :return: An OpenAI client
+        :return: The NVIDIA API base URL
         """
-
+        return f"{self._config.url}/v1" if self._config.append_api_version else self._config.url
-        base_url = f"{self._config.url}/v1" if self._config.append_api_version else self._config.url
-
-        return AsyncOpenAI(
-            base_url=base_url,
-            api_key=(self._config.api_key.get_secret_value() if self._config.api_key else "NO KEY"),
-            timeout=self._config.timeout,
-        )
-
-    async def _get_provider_model_id(self, model_id: str) -> str:
-        if not self.model_store:
-            raise RuntimeError("Model store is not set")
-        model = await self.model_store.get_model(model_id)
-        if model is None:
-            raise ValueError(f"Model {model_id} is unknown")
-        return model.provider_model_id
 
     async def completion(
         self,
@@ -160,7 +142,7 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
         )
 
         try:
-            response = await self._client.completions.create(**request)
+            response = await self.client.completions.create(**request)
         except APIConnectionError as e:
             raise ConnectionError(f"Failed to connect to NVIDIA NIM at {self._config.url}: {e}") from e
 
@@ -213,7 +195,7 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
             extra_body["input_type"] = task_type_options[task_type]
 
         try:
-            response = await self._client.embeddings.create(
+            response = await self.client.embeddings.create(
                 model=provider_model_id,
                 input=input,
                 extra_body=extra_body,
@@ -228,16 +210,6 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
         #
         return EmbeddingsResponse(embeddings=[embedding.embedding for embedding in response.data])
 
-    async def openai_embeddings(
-        self,
-        model: str,
-        input: str | list[str],
-        encoding_format: str | None = "float",
-        dimensions: int | None = None,
-        user: str | None = None,
-    ) -> OpenAIEmbeddingsResponse:
-        raise NotImplementedError()
-
     async def chat_completion(
         self,
         model_id: str,
@@ -274,7 +246,7 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
         )
 
         try:
-            response = await self._client.chat.completions.create(**request)
+            response = await self.client.chat.completions.create(**request)
         except APIConnectionError as e:
             raise ConnectionError(f"Failed to connect to NVIDIA NIM at {self._config.url}: {e}") from e
 
@@ -283,112 +255,3 @@ class NVIDIAInferenceAdapter(Inference, ModelRegistryHelper):
         else:
             # we pass n=1 to get only one completion
             return convert_openai_chat_completion_choice(response.choices[0])
-
-    async def openai_completion(
-        self,
-        model: str,
-        prompt: str | list[str] | list[int] | list[list[int]],
-        best_of: int | None = None,
-        echo: bool | None = None,
-        frequency_penalty: float | None = None,
-        logit_bias: dict[str, float] | None = None,
-        logprobs: bool | None = None,
-        max_tokens: int | None = None,
-        n: int | None = None,
-        presence_penalty: float | None = None,
-        seed: int | None = None,
-        stop: str | list[str] | None = None,
-        stream: bool | None = None,
-        stream_options: dict[str, Any] | None = None,
-        temperature: float | None = None,
-        top_p: float | None = None,
-        user: str | None = None,
-        guided_choice: list[str] | None = None,
-        prompt_logprobs: int | None = None,
-        suffix: str | None = None,
-    ) -> OpenAICompletion:
-        provider_model_id = await self._get_provider_model_id(model)
-
-        params = await prepare_openai_completion_params(
-            model=provider_model_id,
-            prompt=prompt,
-            best_of=best_of,
-            echo=echo,
-            frequency_penalty=frequency_penalty,
-            logit_bias=logit_bias,
-            logprobs=logprobs,
-            max_tokens=max_tokens,
-            n=n,
-            presence_penalty=presence_penalty,
-            seed=seed,
-            stop=stop,
-            stream=stream,
-            stream_options=stream_options,
-            temperature=temperature,
-            top_p=top_p,
-            user=user,
-        )
-
-        try:
-            return await self._client.completions.create(**params)
-        except APIConnectionError as e:
-            raise ConnectionError(f"Failed to connect to NVIDIA NIM at {self._config.url}: {e}") from e
-
-    async def openai_chat_completion(
-        self,
-        model: str,
-        messages: list[OpenAIMessageParam],
-        frequency_penalty: float | None = None,
-        function_call: str | dict[str, Any] | None = None,
-        functions: list[dict[str, Any]] | None = None,
-        logit_bias: dict[str, float] | None = None,
-        logprobs: bool | None = None,
-        max_completion_tokens: int | None = None,
-        max_tokens: int | None = None,
-        n: int | None = None,
-        parallel_tool_calls: bool | None = None,
-        presence_penalty: float | None = None,
-        response_format: OpenAIResponseFormatParam | None = None,
-        seed: int | None = None,
-        stop: str | list[str] | None = None,
-        stream: bool | None = None,
-        stream_options: dict[str, Any] | None = None,
-        temperature: float | None = None,
-        tool_choice: str | dict[str, Any] | None = None,
-        tools: list[dict[str, Any]] | None = None,
-        top_logprobs: int | None = None,
-        top_p: float | None = None,
-        user: str | None = None,
-    ) -> OpenAIChatCompletion | AsyncIterator[OpenAIChatCompletionChunk]:
-        provider_model_id = await self._get_provider_model_id(model)
-
-        params = await prepare_openai_completion_params(
-            model=provider_model_id,
-            messages=messages,
-            frequency_penalty=frequency_penalty,
-            function_call=function_call,
-            functions=functions,
-            logit_bias=logit_bias,
-            logprobs=logprobs,
-            max_completion_tokens=max_completion_tokens,
-            max_tokens=max_tokens,
-            n=n,
-            parallel_tool_calls=parallel_tool_calls,
-            presence_penalty=presence_penalty,
-            response_format=response_format,
-            seed=seed,
-            stop=stop,
-            stream=stream,
-            stream_options=stream_options,
-            temperature=temperature,
-            tool_choice=tool_choice,
-            tools=tools,
-            top_logprobs=top_logprobs,
-            top_p=top_p,
-            user=user,
-        )
-
-        try:
-            return await self._client.chat.completions.create(**params)
-        except APIConnectionError as e:
-            raise ConnectionError(f"Failed to connect to NVIDIA NIM at {self._config.url}: {e}") from e

llama_stack/providers/remote/inference/openai/openai.py

@@ -5,23 +5,9 @@
 # the root directory of this source tree.
 
 import logging
-from collections.abc import AsyncIterator
-from typing import Any
 
-from openai import AsyncOpenAI, NotFoundError
-
-from llama_stack.apis.inference import (
-    OpenAIChatCompletion,
-    OpenAIChatCompletionChunk,
-    OpenAICompletion,
-    OpenAIEmbeddingData,
-    OpenAIEmbeddingsResponse,
-    OpenAIEmbeddingUsage,
-    OpenAIMessageParam,
-    OpenAIResponseFormatParam,
-)
 from llama_stack.providers.utils.inference.litellm_openai_mixin import LiteLLMOpenAIMixin
-from llama_stack.providers.utils.inference.openai_compat import prepare_openai_completion_params
+from llama_stack.providers.utils.inference.openai_mixin import OpenAIMixin
 
 from .config import OpenAIConfig
 from .models import MODEL_ENTRIES
@@ -30,7 +16,7 @@ logger = logging.getLogger(__name__)
 
 
 #
-# This OpenAI adapter implements Inference methods using two clients -
+# This OpenAI adapter implements Inference methods using two mixins -
 #
 # | Inference Method           | Implementation Source    |
 # |----------------------------|--------------------------|
@@ -39,11 +25,22 @@ logger = logging.getLogger(__name__)
 # | embedding                  | LiteLLMOpenAIMixin       |
 # | batch_completion           | LiteLLMOpenAIMixin       |
 # | batch_chat_completion      | LiteLLMOpenAIMixin       |
-# | openai_completion          | AsyncOpenAI              |
+# | openai_completion          | OpenAIMixin              |
-# | openai_chat_completion     | AsyncOpenAI              |
+# | openai_chat_completion     | OpenAIMixin              |
-# | openai_embeddings          | AsyncOpenAI              |
+# | openai_embeddings          | OpenAIMixin              |
 #
-class OpenAIInferenceAdapter(LiteLLMOpenAIMixin):
+class OpenAIInferenceAdapter(OpenAIMixin, LiteLLMOpenAIMixin):
+    """
+    OpenAI Inference Adapter for Llama Stack.
+
+    Note: The inheritance order is important here. OpenAIMixin must come before
+    LiteLLMOpenAIMixin to ensure that OpenAIMixin.check_model_availability()
+    is used instead of ModelRegistryHelper.check_model_availability().
+
+    - OpenAIMixin.check_model_availability() queries the OpenAI API to check if a model exists
+    - ModelRegistryHelper.check_model_availability() (inherited by LiteLLMOpenAIMixin) just returns False and shows a warning
+    """
+
     def __init__(self, config: OpenAIConfig) -> None:
         LiteLLMOpenAIMixin.__init__(
             self,
@@ -60,191 +57,19 @@ class OpenAIInferenceAdapter(LiteLLMOpenAIMixin):
         # litellm specific model names, an abstraction leak.
         self.is_openai_compat = True
 
-    async def check_model_availability(self, model: str) -> bool:
+    # Delegate the client data handling get_api_key method to LiteLLMOpenAIMixin
+    get_api_key = LiteLLMOpenAIMixin.get_api_key
+
+    def get_base_url(self) -> str:
         """
-        Check if a specific model is available from OpenAI.
+        Get the OpenAI API base URL.
 
-        :param model: The model identifier to check.
+        Returns the standard OpenAI API base URL for direct OpenAI API calls.
-        :return: True if the model is available dynamically, False otherwise.
         """
-        try:
+        return "https://api.openai.com/v1"
-            openai_client = self._get_openai_client()
-            retrieved_model = await openai_client.models.retrieve(model)
-            logger.info(f"Model {retrieved_model.id} is available from OpenAI")
-            return True
-
-        except NotFoundError:
-            logger.error(f"Model {model} is not available from OpenAI")
-            return False
-
-        except Exception as e:
-            logger.error(f"Failed to check model availability from OpenAI: {e}")
-            return False
 
     async def initialize(self) -> None:
         await super().initialize()
 
     async def shutdown(self) -> None:
         await super().shutdown()
-
-    def _get_openai_client(self) -> AsyncOpenAI:
-        return AsyncOpenAI(
-            api_key=self.get_api_key(),
-        )
-
-    async def openai_completion(
-        self,
-        model: str,
-        prompt: str | list[str] | list[int] | list[list[int]],
-        best_of: int | None = None,
-        echo: bool | None = None,
-        frequency_penalty: float | None = None,
-        logit_bias: dict[str, float] | None = None,
-        logprobs: bool | None = None,
-        max_tokens: int | None = None,
-        n: int | None = None,
-        presence_penalty: float | None = None,
-        seed: int | None = None,
-        stop: str | list[str] | None = None,
-        stream: bool | None = None,
-        stream_options: dict[str, Any] | None = None,
-        temperature: float | None = None,
-        top_p: float | None = None,
-        user: str | None = None,
-        guided_choice: list[str] | None = None,
-        prompt_logprobs: int | None = None,
-        suffix: str | None = None,
-    ) -> OpenAICompletion:
-        if guided_choice is not None:
-            logging.warning("guided_choice is not supported by the OpenAI API. Ignoring.")
-        if prompt_logprobs is not None:
-            logging.warning("prompt_logprobs is not supported by the OpenAI API. Ignoring.")
-
-        model_id = (await self.model_store.get_model(model)).provider_resource_id
-        if model_id.startswith("openai/"):
-            model_id = model_id[len("openai/") :]
-        params = await prepare_openai_completion_params(
-            model=model_id,
-            prompt=prompt,
-            best_of=best_of,
-            echo=echo,
-            frequency_penalty=frequency_penalty,
-            logit_bias=logit_bias,
-            logprobs=logprobs,
-            max_tokens=max_tokens,
-            n=n,
-            presence_penalty=presence_penalty,
-            seed=seed,
-            stop=stop,
-            stream=stream,
-            stream_options=stream_options,
-            temperature=temperature,
-            top_p=top_p,
-            user=user,
-            suffix=suffix,
-        )
-        return await self._get_openai_client().completions.create(**params)
-
-    async def openai_chat_completion(
-        self,
-        model: str,
-        messages: list[OpenAIMessageParam],
-        frequency_penalty: float | None = None,
-        function_call: str | dict[str, Any] | None = None,
-        functions: list[dict[str, Any]] | None = None,
-        logit_bias: dict[str, float] | None = None,
-        logprobs: bool | None = None,
-        max_completion_tokens: int | None = None,
-        max_tokens: int | None = None,
-        n: int | None = None,
-        parallel_tool_calls: bool | None = None,
-        presence_penalty: float | None = None,
-        response_format: OpenAIResponseFormatParam | None = None,
-        seed: int | None = None,
-        stop: str | list[str] | None = None,
-        stream: bool | None = None,
-        stream_options: dict[str, Any] | None = None,
-        temperature: float | None = None,
-        tool_choice: str | dict[str, Any] | None = None,
-        tools: list[dict[str, Any]] | None = None,
-        top_logprobs: int | None = None,
-        top_p: float | None = None,
-        user: str | None = None,
-    ) -> OpenAIChatCompletion | AsyncIterator[OpenAIChatCompletionChunk]:
-        model_id = (await self.model_store.get_model(model)).provider_resource_id
-        if model_id.startswith("openai/"):
-            model_id = model_id[len("openai/") :]
-        params = await prepare_openai_completion_params(
-            model=model_id,
-            messages=messages,
-            frequency_penalty=frequency_penalty,
-            function_call=function_call,
-            functions=functions,
-            logit_bias=logit_bias,
-            logprobs=logprobs,
-            max_completion_tokens=max_completion_tokens,
-            max_tokens=max_tokens,
-            n=n,
-            parallel_tool_calls=parallel_tool_calls,
-            presence_penalty=presence_penalty,
-            response_format=response_format,
-            seed=seed,
-            stop=stop,
-            stream=stream,
-            stream_options=stream_options,
-            temperature=temperature,
-            tool_choice=tool_choice,
-            tools=tools,
-            top_logprobs=top_logprobs,
-            top_p=top_p,
-            user=user,
-        )
-        return await self._get_openai_client().chat.completions.create(**params)
-
-    async def openai_embeddings(
-        self,
-        model: str,
-        input: str | list[str],
-        encoding_format: str | None = "float",
-        dimensions: int | None = None,
-        user: str | None = None,
-    ) -> OpenAIEmbeddingsResponse:
-        model_id = (await self.model_store.get_model(model)).provider_resource_id
-        if model_id.startswith("openai/"):
-            model_id = model_id[len("openai/") :]
-
-        # Prepare parameters for OpenAI embeddings API
-        params = {
-            "model": model_id,
-            "input": input,
-        }
-
-        if encoding_format is not None:
-            params["encoding_format"] = encoding_format
-        if dimensions is not None:
-            params["dimensions"] = dimensions
-        if user is not None:
-            params["user"] = user
-
-        # Call OpenAI embeddings API
-        response = await self._get_openai_client().embeddings.create(**params)
-
-        data = []
-        for i, embedding_data in enumerate(response.data):
-            data.append(
-                OpenAIEmbeddingData(
-                    embedding=embedding_data.embedding,
-                    index=i,
-                )
-            )
-
-        usage = OpenAIEmbeddingUsage(
-            prompt_tokens=response.usage.prompt_tokens,
-            total_tokens=response.usage.total_tokens,
-        )
-
-        return OpenAIEmbeddingsResponse(
-            data=data,
-            model=response.model,
-            usage=usage,
-        )

llama_stack/providers/utils/inference/model_registry.py

@@ -10,12 +10,15 @@ from pydantic import BaseModel, Field
 
 from llama_stack.apis.common.errors import UnsupportedModelError
 from llama_stack.apis.models import ModelType
+from llama_stack.log import get_logger
 from llama_stack.models.llama.sku_list import all_registered_models
 from llama_stack.providers.datatypes import Model, ModelsProtocolPrivate
 from llama_stack.providers.utils.inference import (
     ALL_HUGGINGFACE_REPOS_TO_MODEL_DESCRIPTOR,
 )
 
+logger = get_logger(name=__name__, category="core")
+
 
 # TODO: this class is more confusing than useful right now. We need to make it
 # more closer to the Model class.
@@ -98,6 +101,9 @@ class ModelRegistryHelper(ModelsProtocolPrivate):
         :param model: The model identifier to check.
         :return: True if the model is available dynamically, False otherwise.
         """
+        logger.info(
+            f"check_model_availability is not implemented for {self.__class__.__name__}. Returning False by default."
+        )
         return False
 
     async def register_model(self, model: Model) -> Model:

llama_stack/providers/utils/inference/openai_mixin.py

@@ -0,0 +1,272 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from abc import ABC, abstractmethod
+from collections.abc import AsyncIterator
+from typing import Any
+
+import openai
+from openai import NOT_GIVEN, AsyncOpenAI
+
+from llama_stack.apis.inference import (
+    Model,
+    OpenAIChatCompletion,
+    OpenAIChatCompletionChunk,
+    OpenAICompletion,
+    OpenAIEmbeddingData,
+    OpenAIEmbeddingsResponse,
+    OpenAIEmbeddingUsage,
+    OpenAIMessageParam,
+    OpenAIResponseFormatParam,
+)
+from llama_stack.log import get_logger
+from llama_stack.providers.utils.inference.openai_compat import prepare_openai_completion_params
+
+logger = get_logger(name=__name__, category="core")
+
+
+class OpenAIMixin(ABC):
+    """
+    Mixin class that provides OpenAI-specific functionality for inference providers.
+    This class handles direct OpenAI API calls using the AsyncOpenAI client.
+
+    This is an abstract base class that requires child classes to implement:
+    - get_api_key(): Method to retrieve the API key
+    - get_base_url(): Method to retrieve the OpenAI-compatible API base URL
+
+    Expected Dependencies:
+    - self.model_store: Injected by the Llama Stack distribution system at runtime.
+      This provides model registry functionality for looking up registered models.
+      The model_store is set in routing_tables/common.py during provider initialization.
+    """
+
+    @abstractmethod
+    def get_api_key(self) -> str:
+        """
+        Get the API key.
+
+        This method must be implemented by child classes to provide the API key
+        for authenticating with the OpenAI API or compatible endpoints.
+
+        :return: The API key as a string
+        """
+        pass
+
+    @abstractmethod
+    def get_base_url(self) -> str:
+        """
+        Get the OpenAI-compatible API base URL.
+
+        This method must be implemented by child classes to provide the base URL
+        for the OpenAI API or compatible endpoints (e.g., "https://api.openai.com/v1").
+
+        :return: The base URL as a string
+        """
+        pass
+
+    @property
+    def client(self) -> AsyncOpenAI:
+        """
+        Get an AsyncOpenAI client instance.
+
+        Uses the abstract methods get_api_key() and get_base_url() which must be
+        implemented by child classes.
+        """
+        return AsyncOpenAI(
+            api_key=self.get_api_key(),
+            base_url=self.get_base_url(),
+        )
+
+    async def _get_provider_model_id(self, model: str) -> str:
+        """
+        Get the provider-specific model ID from the model store.
+
+        This is a utility method that looks up the registered model and returns
+        the provider_resource_id that should be used for actual API calls.
+
+        :param model: The registered model name/identifier
+        :return: The provider-specific model ID (e.g., "gpt-4")
+        """
+        # Look up the registered model to get the provider-specific model ID
+        # self.model_store is injected by the distribution system at runtime
+        model_obj: Model = await self.model_store.get_model(model)  # type: ignore[attr-defined]
+        # provider_resource_id is str | None, but we expect it to be str for OpenAI calls
+        if model_obj.provider_resource_id is None:
+            raise ValueError(f"Model {model} has no provider_resource_id")
+        return model_obj.provider_resource_id
+
+    async def openai_completion(
+        self,
+        model: str,
+        prompt: str | list[str] | list[int] | list[list[int]],
+        best_of: int | None = None,
+        echo: bool | None = None,
+        frequency_penalty: float | None = None,
+        logit_bias: dict[str, float] | None = None,
+        logprobs: bool | None = None,
+        max_tokens: int | None = None,
+        n: int | None = None,
+        presence_penalty: float | None = None,
+        seed: int | None = None,
+        stop: str | list[str] | None = None,
+        stream: bool | None = None,
+        stream_options: dict[str, Any] | None = None,
+        temperature: float | None = None,
+        top_p: float | None = None,
+        user: str | None = None,
+        guided_choice: list[str] | None = None,
+        prompt_logprobs: int | None = None,
+        suffix: str | None = None,
+    ) -> OpenAICompletion:
+        """
+        Direct OpenAI completion API call.
+        """
+        if guided_choice is not None:
+            logger.warning("guided_choice is not supported by the OpenAI API. Ignoring.")
+        if prompt_logprobs is not None:
+            logger.warning("prompt_logprobs is not supported by the OpenAI API. Ignoring.")
+
+        # TODO: fix openai_completion to return type compatible with OpenAI's API response
+        return await self.client.completions.create(  # type: ignore[no-any-return]
+            **await prepare_openai_completion_params(
+                model=await self._get_provider_model_id(model),
+                prompt=prompt,
+                best_of=best_of,
+                echo=echo,
+                frequency_penalty=frequency_penalty,
+                logit_bias=logit_bias,
+                logprobs=logprobs,
+                max_tokens=max_tokens,
+                n=n,
+                presence_penalty=presence_penalty,
+                seed=seed,
+                stop=stop,
+                stream=stream,
+                stream_options=stream_options,
+                temperature=temperature,
+                top_p=top_p,
+                user=user,
+                suffix=suffix,
+            )
+        )
+
+    async def openai_chat_completion(
+        self,
+        model: str,
+        messages: list[OpenAIMessageParam],
+        frequency_penalty: float | None = None,
+        function_call: str | dict[str, Any] | None = None,
+        functions: list[dict[str, Any]] | None = None,
+        logit_bias: dict[str, float] | None = None,
+        logprobs: bool | None = None,
+        max_completion_tokens: int | None = None,
+        max_tokens: int | None = None,
+        n: int | None = None,
+        parallel_tool_calls: bool | None = None,
+        presence_penalty: float | None = None,
+        response_format: OpenAIResponseFormatParam | None = None,
+        seed: int | None = None,
+        stop: str | list[str] | None = None,
+        stream: bool | None = None,
+        stream_options: dict[str, Any] | None = None,
+        temperature: float | None = None,
+        tool_choice: str | dict[str, Any] | None = None,
+        tools: list[dict[str, Any]] | None = None,
+        top_logprobs: int | None = None,
+        top_p: float | None = None,
+        user: str | None = None,
+    ) -> OpenAIChatCompletion | AsyncIterator[OpenAIChatCompletionChunk]:
+        """
+        Direct OpenAI chat completion API call.
+        """
+        # Type ignore because return types are compatible
+        return await self.client.chat.completions.create(  # type: ignore[no-any-return]
+            **await prepare_openai_completion_params(
+                model=await self._get_provider_model_id(model),
+                messages=messages,
+                frequency_penalty=frequency_penalty,
+                function_call=function_call,
+                functions=functions,
+                logit_bias=logit_bias,
+                logprobs=logprobs,
+                max_completion_tokens=max_completion_tokens,
+                max_tokens=max_tokens,
+                n=n,
+                parallel_tool_calls=parallel_tool_calls,
+                presence_penalty=presence_penalty,
+                response_format=response_format,
+                seed=seed,
+                stop=stop,
+                stream=stream,
+                stream_options=stream_options,
+                temperature=temperature,
+                tool_choice=tool_choice,
+                tools=tools,
+                top_logprobs=top_logprobs,
+                top_p=top_p,
+                user=user,
+            )
+        )
+
+    async def openai_embeddings(
+        self,
+        model: str,
+        input: str | list[str],
+        encoding_format: str | None = "float",
+        dimensions: int | None = None,
+        user: str | None = None,
+    ) -> OpenAIEmbeddingsResponse:
+        """
+        Direct OpenAI embeddings API call.
+        """
+        # Call OpenAI embeddings API with properly typed parameters
+        response = await self.client.embeddings.create(
+            model=await self._get_provider_model_id(model),
+            input=input,
+            encoding_format=encoding_format if encoding_format is not None else NOT_GIVEN,
+            dimensions=dimensions if dimensions is not None else NOT_GIVEN,
+            user=user if user is not None else NOT_GIVEN,
+        )
+
+        data = []
+        for i, embedding_data in enumerate(response.data):
+            data.append(
+                OpenAIEmbeddingData(
+                    embedding=embedding_data.embedding,
+                    index=i,
+                )
+            )
+
+        usage = OpenAIEmbeddingUsage(
+            prompt_tokens=response.usage.prompt_tokens,
+            total_tokens=response.usage.total_tokens,
+        )
+
+        return OpenAIEmbeddingsResponse(
+            data=data,
+            model=response.model,
+            usage=usage,
+        )
+
+    async def check_model_availability(self, model: str) -> bool:
+        """
+        Check if a specific model is available from OpenAI.
+
+        :param model: The model identifier to check.
+        :return: True if the model is available dynamically, False otherwise.
+        """
+        try:
+            # Direct model lookup - returns model or raises NotFoundError
+            await self.client.models.retrieve(model)
+            return True
+        except openai.NotFoundError:
+            # Model doesn't exist - this is expected for unavailable models
+            pass
+        except Exception as e:
+            # All other errors (auth, rate limit, network, etc.)
+            logger.warning(f"Failed to check model availability for {model}: {e}")
+
+        return False

tests/unit/providers/inference/test_inference_client_caching.py

@@ -10,6 +10,8 @@ from unittest.mock import MagicMock
 from llama_stack.distribution.request_headers import request_provider_data_context
 from llama_stack.providers.remote.inference.groq.config import GroqConfig
 from llama_stack.providers.remote.inference.groq.groq import GroqInferenceAdapter
+from llama_stack.providers.remote.inference.llama_openai_compat.config import LlamaCompatConfig
+from llama_stack.providers.remote.inference.llama_openai_compat.llama import LlamaCompatInferenceAdapter
 from llama_stack.providers.remote.inference.openai.config import OpenAIConfig
 from llama_stack.providers.remote.inference.openai.openai import OpenAIInferenceAdapter
 from llama_stack.providers.remote.inference.together.config import TogetherImplConfig
@@ -50,7 +52,7 @@ def test_openai_provider_openai_client_caching():
         with request_provider_data_context(
             {"x-llamastack-provider-data": json.dumps({inference_adapter.provider_data_api_key_field: api_key})}
         ):
-            openai_client = inference_adapter._get_openai_client()
+            openai_client = inference_adapter.client
             assert openai_client.api_key == api_key
 
 
@@ -71,3 +73,18 @@ def test_together_provider_openai_client_caching():
             assert together_client.client.api_key == api_key
             openai_client = inference_adapter._get_openai_client()
             assert openai_client.api_key == api_key
+
+
+def test_llama_compat_provider_openai_client_caching():
+    """Ensure the LlamaCompat provider does not cache api keys across client requests"""
+    config = LlamaCompatConfig()
+    inference_adapter = LlamaCompatInferenceAdapter(config)
+
+    inference_adapter.__provider_spec__ = MagicMock()
+    inference_adapter.__provider_spec__.provider_data_validator = (
+        "llama_stack.providers.remote.inference.llama_openai_compat.config.LlamaProviderDataValidator"
+    )
+
+    for api_key in ["test1", "test2"]:
+        with request_provider_data_context({"x-llamastack-provider-data": json.dumps({"llama_api_key": api_key})}):
+            assert inference_adapter.client.api_key == api_key