[Bugfix][Frontend] Stop SSL certificate watchers when HTTP serving exits (#55699)

Signed-off-by: git-jxj <65210887+git-jxj@users.noreply.github.com>
Co-authored-by: OpenAI Codex <noreply@openai.com>

tests/entrypoints/launchers/test_ssl_cert_refresher.py

@@ -4,9 +4,12 @@ import asyncio
 import tempfile
 from pathlib import Path
 from ssl import SSLContext
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock
 
 import pytest
 
+from vllm.entrypoints.launchers import launcher
 from vllm.entrypoints.launchers.utils.ssl import SSLCertRefresher
 
 
@@ -100,3 +103,66 @@ async def test_ssl_refresher():
     await asyncio.sleep(1)
     assert ssl_context.load_cert_chain_count == cert_chain_count
     assert ssl_context.load_ca_count == ca_count
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("failure_stage", [None, "serve", "signal", "shutdown_task"])
+async def test_serve_http_stops_ssl_refresher_when_server_exits(
+    monkeypatch, failure_stage
+):
+    config = SimpleNamespace(
+        ssl=object(),
+        ssl_keyfile="key.pem",
+        ssl_certfile="cert.pem",
+        ssl_ca_certs="ca.pem",
+        load=MagicMock(),
+    )
+    server_error = RuntimeError("server failed") if failure_stage == "serve" else None
+    server = SimpleNamespace(serve=AsyncMock(side_effect=server_error))
+    ssl_cert_refresher = MagicMock()
+    loop = asyncio.get_running_loop()
+
+    def add_signal_handler(*_args):
+        if failure_stage == "signal":
+            raise RuntimeError("signal failed")
+
+    create_task = loop.create_task
+
+    def create_task_or_fail(coro, **kwargs):
+        if (
+            failure_stage == "shutdown_task"
+            and coro.cr_code.co_name == "handle_shutdown"
+        ):
+            coro.close()
+            raise RuntimeError("shutdown_task failed")
+        return create_task(coro, **kwargs)
+
+    monkeypatch.setattr(loop, "add_signal_handler", add_signal_handler)
+    monkeypatch.setattr(loop, "create_task", create_task_or_fail)
+    monkeypatch.setattr(launcher.uvicorn, "Config", lambda *_args, **_kwargs: config)
+    monkeypatch.setattr(launcher, "NoSignalServer", lambda _config: server)
+    monkeypatch.setattr(
+        launcher,
+        "SSLCertRefresher",
+        lambda **_kwargs: ssl_cert_refresher,
+    )
+    monkeypatch.setattr(launcher, "watchdog_loop", AsyncMock())
+    app = SimpleNamespace(routes=[], state=SimpleNamespace(engine_client=object()))
+
+    shutdown = None
+    try:
+        if failure_stage is None:
+            shutdown = await launcher.serve_http(
+                app, sock=None, enable_ssl_refresh=True, port=8000
+            )
+        else:
+            error = "server" if failure_stage == "serve" else failure_stage
+            with pytest.raises(RuntimeError, match=f"{error} failed"):
+                await launcher.serve_http(
+                    app, sock=None, enable_ssl_refresh=True, port=8000
+                )
+        ssl_cert_refresher.stop.assert_called_once_with()
+    finally:
+        if shutdown is not None:
+            await shutdown
+        await asyncio.sleep(0)

vllm/entrypoints/launchers/launcher.py

@@ -259,9 +259,6 @@ async def serve_http(
     async def dummy_shutdown() -> None:
         pass
 
-    loop.add_signal_handler(signal.SIGINT, signal_handler)
-    loop.add_signal_handler(signal.SIGTERM, signal_handler)
-
     async def handle_shutdown() -> None:
         await shutdown_event.wait()
 
@@ -285,12 +282,13 @@ async def serve_http(
         server_task.cancel()
         if watchdog_task is not None:
             watchdog_task.cancel()
-        if ssl_cert_refresher:
-            ssl_cert_refresher.stop()
-
-    shutdown_task = loop.create_task(handle_shutdown())
 
+    shutdown_task = None
     try:
+        loop.add_signal_handler(signal.SIGINT, signal_handler)
+        loop.add_signal_handler(signal.SIGTERM, signal_handler)
+        shutdown_task = loop.create_task(handle_shutdown())
+
         await server_task
         return dummy_shutdown()
     except asyncio.CancelledError:
@@ -306,9 +304,12 @@ async def serve_http(
         logger.info_once("[shutdown] API server: shutting down FastAPI HTTP server")
         return server.shutdown()
     finally:
-        shutdown_task.cancel()
+        if shutdown_task is not None:
+            shutdown_task.cancel()
         if watchdog_task is not None:
             watchdog_task.cancel()
+        if ssl_cert_refresher:
+            ssl_cert_refresher.stop()
 
 
 async def watchdog_loop(server: uvicorn.Server, engine: EngineClient):