Sync from v0.13

vllm/entrypoints/serve/elastic_ep/api_router.py

@@ -0,0 +1,96 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+
+import json
+from http import HTTPStatus
+
+from fastapi import APIRouter, Depends, FastAPI, HTTPException, Request
+from fastapi.responses import JSONResponse
+
+from vllm.engine.protocol import EngineClient
+from vllm.entrypoints.openai.api_server import validate_json_request
+from vllm.entrypoints.openai.protocol import (
+    ErrorResponse,
+)
+from vllm.entrypoints.serve.elastic_ep.middleware import (
+    get_scaling_elastic_ep,
+    set_scaling_elastic_ep,
+)
+from vllm.logger import init_logger
+
+logger = init_logger(__name__)
+
+
+def engine_client(request: Request) -> EngineClient:
+    return request.app.state.engine_client
+
+
+router = APIRouter()
+
+
+@router.post(
+    "/scale_elastic_ep",
+    dependencies=[Depends(validate_json_request)],
+    responses={
+        HTTPStatus.OK.value: {"model": dict},
+        HTTPStatus.BAD_REQUEST.value: {"model": ErrorResponse},
+        HTTPStatus.REQUEST_TIMEOUT.value: {"model": ErrorResponse},
+        HTTPStatus.INTERNAL_SERVER_ERROR.value: {"model": ErrorResponse},
+    },
+)
+async def scale_elastic_ep(raw_request: Request):
+    try:
+        body = await raw_request.json()
+    except json.JSONDecodeError as e:
+        raise HTTPException(status_code=400, detail="Invalid JSON format") from e  # noqa: B904
+
+    new_data_parallel_size = body.get("new_data_parallel_size")
+    drain_timeout = body.get("drain_timeout", 120)  # Default 2 minutes
+
+    if new_data_parallel_size is None:
+        raise HTTPException(
+            status_code=400, detail="new_data_parallel_size is required"
+        )
+
+    if not isinstance(new_data_parallel_size, int) or new_data_parallel_size <= 0:
+        raise HTTPException(
+            status_code=400,
+            detail="new_data_parallel_size must be a positive integer",
+        )
+
+    if not isinstance(drain_timeout, int) or drain_timeout <= 0:
+        raise HTTPException(
+            status_code=400, detail="drain_timeout must be a positive integer"
+        )
+
+    # Set scaling flag to prevent new requests
+    set_scaling_elastic_ep(True)
+    client = engine_client(raw_request)
+    try:
+        await client.scale_elastic_ep(new_data_parallel_size, drain_timeout)
+        return JSONResponse(
+            {
+                "message": f"Scaled to {new_data_parallel_size} data parallel engines",
+            }
+        )
+    except TimeoutError as e:
+        raise HTTPException(
+            status_code=408,
+            detail="Scale failed due to request drain timeout "
+            f"after {drain_timeout} seconds",
+        ) from e
+    except Exception as e:
+        logger.error("Scale failed: %s", e)
+        raise HTTPException(status_code=500, detail="Scale failed") from e
+    finally:
+        set_scaling_elastic_ep(False)
+
+
+@router.post("/is_scaling_elastic_ep")
+async def is_scaling_elastic_ep(raw_request: Request):
+    return JSONResponse({"is_scaling_elastic_ep": get_scaling_elastic_ep()})
+
+
+def attach_router(app: FastAPI):
+    app.include_router(router)

vllm/entrypoints/serve/elastic_ep/middleware.py

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from collections.abc import Awaitable
+
+from fastapi.responses import JSONResponse
+from starlette.types import ASGIApp, Receive, Scope, Send
+
+# Global variable to track scaling state
+_scaling_elastic_ep = False
+
+
+def get_scaling_elastic_ep():
+    return _scaling_elastic_ep
+
+
+def set_scaling_elastic_ep(value):
+    global _scaling_elastic_ep
+    _scaling_elastic_ep = value
+
+
+class ScalingMiddleware:
+    """
+    Middleware that checks if the model is currently scaling and
+    returns a 503 Service Unavailable response if it is.
+
+    This middleware applies to all HTTP requests and prevents
+    processing when the model is in a scaling state.
+    """
+
+    def __init__(self, app: ASGIApp) -> None:
+        self.app = app
+
+    def __call__(self, scope: Scope, receive: Receive, send: Send) -> Awaitable[None]:
+        if scope["type"] != "http":
+            return self.app(scope, receive, send)
+
+        # Check global scaling state
+        if get_scaling_elastic_ep():
+            # Return 503 Service Unavailable response
+            response = JSONResponse(
+                content={
+                    "error": "The model is currently scaling. Please try again later."
+                },
+                status_code=503,
+            )
+            return response(scope, receive, send)
+
+        return self.app(scope, receive, send)