feat: OpenAI-Compatible models, completions, chat/completions (#1894)

# What does this PR do?

This stubs in some OpenAI server-side compatibility with three new
endpoints:

/v1/openai/v1/models
/v1/openai/v1/completions
/v1/openai/v1/chat/completions

This gives common inference apps using OpenAI clients the ability to
talk to Llama Stack using an endpoint like
http://localhost:8321/v1/openai/v1 .

The two "v1" instances in there isn't awesome, but the thinking is that
Llama Stack's API is v1 and then our OpenAI compatibility layer is
compatible with OpenAI V1. And, some OpenAI clients implicitly assume
the URL ends with "v1", so this gives maximum compatibility.

The openai models endpoint is implemented in the routing layer, and just
returns all the models Llama Stack knows about.

The following providers should be working with the new OpenAI
completions and chat/completions API:
* remote::anthropic (untested)
* remote::cerebras-openai-compat (untested)
* remote::fireworks (tested)
* remote::fireworks-openai-compat (untested)
* remote::gemini (untested)
* remote::groq-openai-compat (untested)
* remote::nvidia (tested)
* remote::ollama (tested)
* remote::openai (untested)
* remote::passthrough (untested)
* remote::sambanova-openai-compat (untested)
* remote::together (tested)
* remote::together-openai-compat (untested)
* remote::vllm (tested)

The goal to support this for every inference provider - proxying
directly to the provider's OpenAI endpoint for OpenAI-compatible
providers. For providers that don't have an OpenAI-compatible API, we'll
add a mixin to translate incoming OpenAI requests to Llama Stack
inference requests and translate the Llama Stack inference responses to
OpenAI responses.

This is related to #1817 but is a bit larger in scope than just chat
completions, as I have real use-cases that need the older completions
API as well.

## Test Plan

### vLLM

```
VLLM_URL="http://localhost:8000/v1" INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct" llama stack build --template remote-vllm --image-type venv --run

LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "meta-llama/Llama-3.2-3B-Instruct"
```

### ollama
```
INFERENCE_MODEL="llama3.2:3b-instruct-q8_0" llama stack build --template ollama --image-type venv --run

LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="llama3.2:3b-instruct-q8_0" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "llama3.2:3b-instruct-q8_0"
```



## Documentation

Run a Llama Stack distribution that uses one of the providers mentioned
in the list above. Then, use your favorite OpenAI client to send
completion or chat completion requests with the base_url set to
http://localhost:8321/v1/openai/v1 . Replace "localhost:8321" with the
host and port of your Llama Stack server, if different.

---------

Signed-off-by: Ben Browning <bbrownin@redhat.com>
This commit is contained in:
Ben Browning 2025-04-11 16:14:17 -04:00 committed by GitHub
parent 24d70cedca
commit 2b2db5fbda
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27 changed files with 3265 additions and 20 deletions

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@ -5,8 +5,10 @@
# the root directory of this source tree.
import json
import logging
import time
import uuid
import warnings
from typing import AsyncGenerator, Dict, Iterable, List, Optional, Union
from typing import Any, AsyncGenerator, Dict, Iterable, List, Optional, Union
from openai import AsyncStream
from openai.types.chat import (
@ -83,6 +85,7 @@ from llama_stack.apis.inference import (
TopPSamplingStrategy,
UserMessage,
)
from llama_stack.apis.inference.inference import OpenAIChatCompletion, OpenAICompletion, OpenAICompletionChoice
from llama_stack.models.llama.datatypes import (
BuiltinTool,
StopReason,
@ -843,6 +846,31 @@ def _convert_openai_logprobs(
]
def _convert_openai_sampling_params(
max_tokens: Optional[int] = None,
temperature: Optional[float] = None,
top_p: Optional[float] = None,
) -> SamplingParams:
sampling_params = SamplingParams()
if max_tokens:
sampling_params.max_tokens = max_tokens
# Map an explicit temperature of 0 to greedy sampling
if temperature == 0:
strategy = GreedySamplingStrategy()
else:
# OpenAI defaults to 1.0 for temperature and top_p if unset
if temperature is None:
temperature = 1.0
if top_p is None:
top_p = 1.0
strategy = TopPSamplingStrategy(temperature=temperature, top_p=top_p)
sampling_params.strategy = strategy
return sampling_params
def convert_openai_chat_completion_choice(
choice: OpenAIChoice,
) -> ChatCompletionResponse:
@ -1049,3 +1077,106 @@ async def convert_openai_chat_completion_stream(
stop_reason=stop_reason,
)
)
async def prepare_openai_completion_params(**params):
completion_params = {k: v for k, v in params.items() if v is not None}
return completion_params
class OpenAICompletionUnsupportedMixin:
async def openai_completion(
self,
model: str,
prompt: Union[str, List[str], List[int], List[List[int]]],
best_of: Optional[int] = None,
echo: Optional[bool] = None,
frequency_penalty: Optional[float] = None,
logit_bias: Optional[Dict[str, float]] = None,
logprobs: Optional[bool] = None,
max_tokens: Optional[int] = None,
n: Optional[int] = None,
presence_penalty: Optional[float] = None,
seed: Optional[int] = None,
stop: Optional[Union[str, List[str]]] = None,
stream: Optional[bool] = None,
stream_options: Optional[Dict[str, Any]] = None,
temperature: Optional[float] = None,
top_p: Optional[float] = None,
user: Optional[str] = None,
guided_choice: Optional[List[str]] = None,
prompt_logprobs: Optional[int] = None,
) -> OpenAICompletion:
if stream:
raise ValueError(f"{self.__class__.__name__} doesn't support streaming openai completions")
# This is a pretty hacky way to do emulate completions -
# basically just de-batches them...
prompts = [prompt] if not isinstance(prompt, list) else prompt
sampling_params = _convert_openai_sampling_params(
max_tokens=max_tokens,
temperature=temperature,
top_p=top_p,
)
choices = []
# "n" is the number of completions to generate per prompt
for _i in range(0, n):
# and we may have multiple prompts, if batching was used
for prompt in prompts:
result = self.completion(
model_id=model,
content=prompt,
sampling_params=sampling_params,
)
index = len(choices)
text = result.content
finish_reason = _convert_openai_finish_reason(result.stop_reason)
choice = OpenAICompletionChoice(
index=index,
text=text,
finish_reason=finish_reason,
)
choices.append(choice)
return OpenAICompletion(
id=f"cmpl-{uuid.uuid4()}",
choices=choices,
created=int(time.time()),
model=model,
object="text_completion",
)
class OpenAIChatCompletionUnsupportedMixin:
async def openai_chat_completion(
self,
model: str,
messages: List[OpenAIChatCompletionMessage],
frequency_penalty: Optional[float] = None,
function_call: Optional[Union[str, Dict[str, Any]]] = None,
functions: Optional[List[Dict[str, Any]]] = None,
logit_bias: Optional[Dict[str, float]] = None,
logprobs: Optional[bool] = None,
max_completion_tokens: Optional[int] = None,
max_tokens: Optional[int] = None,
n: Optional[int] = None,
parallel_tool_calls: Optional[bool] = None,
presence_penalty: Optional[float] = None,
response_format: Optional[Dict[str, str]] = None,
seed: Optional[int] = None,
stop: Optional[Union[str, List[str]]] = None,
stream: Optional[bool] = None,
stream_options: Optional[Dict[str, Any]] = None,
temperature: Optional[float] = None,
tool_choice: Optional[Union[str, Dict[str, Any]]] = None,
tools: Optional[List[Dict[str, Any]]] = None,
top_logprobs: Optional[int] = None,
top_p: Optional[float] = None,
user: Optional[str] = None,
) -> OpenAIChatCompletion:
raise ValueError(f"{self.__class__.__name__} doesn't support openai chat completion")