apis/chat_api.py

import argparse
import os
import sys
import uvicorn

from fastapi import FastAPI, Depends
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from pydantic import BaseModel, Field
from typing import Union
from sse_starlette.sse import EventSourceResponse, ServerSentEvent
from utils.logger import logger
from networks.message_streamer import MessageStreamer
from messagers.message_composer import MessageComposer
from mocks.stream_chat_mocker import stream_chat_mock


class ChatAPIApp:
    def __init__(self):
        self.app = FastAPI(
            docs_url="/",
            title="HuggingFace LLM API",
            swagger_ui_parameters={"defaultModelsExpandDepth": -1},
            version="1.0",
        )
        self.setup_routes()

    def get_available_models(self):
        # https://platform.openai.com/docs/api-reference/models/list
        # ANCHOR[id=available-models]: Available models
        self.available_models = {
            "object": "list",
            "data": [
                {
                    "id": "mixtral-8x7b",
                    "description": "[mistralai/Mixtral-8x7B-Instruct-v0.1]: https://huggingface.co/mistralai/Mixtral-8x7B-Instruct-v0.1",
                    "object": "model",
                    "created": 1700000000,
                    "owned_by": "mistralai",
                },
                {
                    "id": "mistral-7b",
                    "description": "[mistralai/Mistral-7B-Instruct-v0.2]: https://huggingface.co/mistralai/Mistral-7B-Instruct-v0.2",
                    "object": "model",
                    "created": 1700000000,
                    "owned_by": "mistralai",
                },
            ],
        }
        return self.available_models

    def extract_api_key(
        credentials: HTTPAuthorizationCredentials = Depends(
            HTTPBearer(auto_error=False)
        ),
    ):
        api_key = None
        if credentials:
            api_key = credentials.credentials
        else:
            api_key = os.getenv("HF_TOKEN")

        if api_key:
            if api_key.startswith("hf_"):
                return api_key
            else:
                logger.warn(f"Invalid HF Token!")
        else:
            logger.warn("Not provide HF Token!")
        return None

    class ChatCompletionsPostItem(BaseModel):
        model: str = Field(
            default="mixtral-8x7b",
            description="(str) `mixtral-8x7b`",
        )
        messages: list = Field(
            default=[{"role": "user", "content": "Hello, who are you?"}],
            description="(list) Messages",
        )
        temperature: Union[float, None] = Field(
            default=0,
            description="(float) Temperature",
        )
        max_tokens: Union[int, None] = Field(
            default=-1,
            description="(int) Max tokens",
        )
        stream: bool = Field(
            default=True,
            description="(bool) Stream",
        )

    def chat_completions(
        self, item: ChatCompletionsPostItem, api_key: str = Depends(extract_api_key)
    ):
        streamer = MessageStreamer(model=item.model)
        composer = MessageComposer(model=item.model)
        composer.merge(messages=item.messages)
        # streamer.chat = stream_chat_mock

        stream_response = streamer.chat_response(
            prompt=composer.merged_str,
            temperature=item.temperature,
            max_new_tokens=item.max_tokens,
            api_key=api_key,
        )
        if item.stream:
            event_source_response = EventSourceResponse(
                streamer.chat_return_generator(stream_response),
                media_type="text/event-stream",
                ping=2000,
                ping_message_factory=lambda: ServerSentEvent(**{"comment": ""}),
            )
            return event_source_response
        else:
            data_response = streamer.chat_return_dict(stream_response)
            return data_response

    def setup_routes(self):
        for prefix in ["", "/v1", "/api", "/api/v1"]:
            self.app.get(
                prefix + "/models",
                summary="Get available models",
            )(self.get_available_models)

            self.app.post(
                prefix + "/chat/completions",
                summary="Chat completions in conversation session",
            )(self.chat_completions)


class ArgParser(argparse.ArgumentParser):
    def __init__(self, *args, **kwargs):
        super(ArgParser, self).__init__(*args, **kwargs)

        self.add_argument(
            "-s",
            "--server",
            type=str,
            default="0.0.0.0",
            help="Server IP for HF LLM Chat API",
        )
        self.add_argument(
            "-p",
            "--port",
            type=int,
            default=23333,
            help="Server Port for HF LLM Chat API",
        )

        self.add_argument(
            "-d",
            "--dev",
            default=False,
            action="store_true",
            help="Run in dev mode",
        )

        self.args = self.parse_args(sys.argv[1:])


app = ChatAPIApp().app

if __name__ == "__main__":
    args = ArgParser().args
    if args.dev:
        uvicorn.run("__main__:app", host=args.server, port=args.port, reload=True)
    else:
        uvicorn.run("__main__:app", host=args.server, port=args.port, reload=False)

    # python -m apis.chat_api      # [Docker] on product mode
    # python -m apis.chat_api -d   # [Dev]    on develop mode