[Frontend] Factor out code for running uvicorn (#6828)

vllm/entrypoints/openai/api_server.py

@@ -2,14 +2,12 @@ import asyncio
 import importlib
 import inspect
 import re
-import signal
+from argparse import Namespace
 from contextlib import asynccontextmanager
 from http import HTTPStatus
-from typing import Optional, Set
+from typing import Any, Optional, Set
 
-import fastapi
-import uvicorn
-from fastapi import APIRouter, Request
+from fastapi import APIRouter, FastAPI, Request
 from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, Response, StreamingResponse
@@ -38,6 +36,7 @@ from vllm.entrypoints.openai.serving_embedding import OpenAIServingEmbedding
 from vllm.entrypoints.openai.serving_tokenization import (
     OpenAIServingTokenization)
 from vllm.logger import init_logger
+from vllm.server import serve_http
 from vllm.usage.usage_lib import UsageContext
 from vllm.utils import FlexibleArgumentParser
 from vllm.version import __version__ as VLLM_VERSION
@@ -57,7 +56,7 @@ _running_tasks: Set[asyncio.Task] = set()
 
 
 @asynccontextmanager
-async def lifespan(app: fastapi.FastAPI):
+async def lifespan(app: FastAPI):
 
     async def _force_log():
         while True:
@@ -75,7 +74,7 @@ async def lifespan(app: fastapi.FastAPI):
 router = APIRouter()
 
 
-def mount_metrics(app: fastapi.FastAPI):
+def mount_metrics(app: FastAPI):
     # Add prometheus asgi middleware to route /metrics requests
     metrics_route = Mount("/metrics", make_asgi_app())
     # Workaround for 307 Redirect for /metrics
@@ -165,8 +164,8 @@ async def create_embedding(request: EmbeddingRequest, raw_request: Request):
         return JSONResponse(content=generator.model_dump())
 
 
-def build_app(args):
-    app = fastapi.FastAPI(lifespan=lifespan)
+def build_app(args: Namespace) -> FastAPI:
+    app = FastAPI(lifespan=lifespan)
     app.include_router(router)
     app.root_path = args.root_path
 
@@ -214,11 +213,8 @@ def build_app(args):
     return app
 
 
-async def build_server(
-    args,
-    llm_engine: Optional[AsyncLLMEngine] = None,
-    **uvicorn_kwargs,
-) -> uvicorn.Server:
+async def init_app(args: Namespace,
+                   llm_engine: Optional[AsyncLLMEngine] = None) -> FastAPI:
     app = build_app(args)
 
     if args.served_model_name is not None:
@@ -281,14 +277,17 @@ async def build_server(
     )
     app.root_path = args.root_path
 
-    logger.info("Available routes are:")
-    for route in app.routes:
-        if not hasattr(route, 'methods'):
-            continue
-        methods = ', '.join(route.methods)
-        logger.info("Route: %s, Methods: %s", route.path, methods)
+    return app
 
-    config = uvicorn.Config(
+
+async def run_server(args: Namespace,
+                     llm_engine: Optional[AsyncLLMEngine] = None,
+                     **uvicorn_kwargs: Any) -> None:
+    logger.info("vLLM API server version %s", VLLM_VERSION)
+    logger.info("args: %s", args)
+
+    app = await init_app(args, llm_engine)
+    await serve_http(
         app,
         host=args.host,
         port=args.port,
@@ -301,36 +300,6 @@ async def build_server(
         **uvicorn_kwargs,
     )
 
-    return uvicorn.Server(config)
-
-
-async def run_server(args, llm_engine=None, **uvicorn_kwargs) -> None:
-    logger.info("vLLM API server version %s", VLLM_VERSION)
-    logger.info("args: %s", args)
-
-    server = await build_server(
-        args,
-        llm_engine,
-        **uvicorn_kwargs,
-    )
-
-    loop = asyncio.get_running_loop()
-
-    server_task = loop.create_task(server.serve())
-
-    def signal_handler() -> None:
-        # prevents the uvicorn signal handler to exit early
-        server_task.cancel()
-
-    loop.add_signal_handler(signal.SIGINT, signal_handler)
-    loop.add_signal_handler(signal.SIGTERM, signal_handler)
-
-    try:
-        await server_task
-    except asyncio.CancelledError:
-        print("Gracefully stopping http server")
-        await server.shutdown()
-
 
 if __name__ == "__main__":
     # NOTE(simon):
@@ -339,4 +308,5 @@ if __name__ == "__main__":
         description="vLLM OpenAI-Compatible RESTful API server.")
     parser = make_arg_parser(parser)
     args = parser.parse_args()
+
     asyncio.run(run_server(args))