fix(iris): fixup Starlette on_shutdown (#4155)

* regression from
https://github.com/marin-community/marin/pull/4126/changes

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ravwojdyla

lib/iris/src/iris/cluster/controller/dashboard.py

@@ -25,8 +25,8 @@
 
 import logging
 import os
-from http.cookies import SimpleCookie
 from collections.abc import Callable
+from http.cookies import SimpleCookie
 from urllib.parse import urlparse
 
 import httpx
@@ -39,7 +39,7 @@
 
 from iris.cluster.controller.actor_proxy import PROXY_ROUTE, ActorProxy
 from iris.cluster.controller.service import ControllerServiceImpl
-from iris.cluster.dashboard_common import html_shell, static_files_mount
+from iris.cluster.dashboard_common import html_shell, on_shutdown, static_files_mount
 from iris.rpc.auth import SESSION_COOKIE, NullAuthInterceptor, TokenVerifier, extract_bearer_token, resolve_auth
 from iris.rpc.cluster_connect import ControllerServiceWSGIApplication
 from iris.rpc.interceptors import RequestTimingInterceptor
@@ -281,9 +281,10 @@ async def _proxy_actor_rpc(request: Request) -> Response:
             Mount(rpc_wsgi_app.path, app=rpc_app),
             static_files_mount(),
         ]
+
         app: Starlette | _RouteAuthMiddleware = Starlette(
             routes=routes,
-            on_shutdown=[self._actor_proxy.close],
+            lifespan=on_shutdown(self._actor_proxy.close),
         )
         if self._auth_verifier is not None and self._auth_provider is not None:
             app = _RouteAuthMiddleware(app, self._auth_verifier, optional=self._auth_optional)
@@ -429,7 +430,8 @@ def _create_app(self) -> Starlette:
             Route("/iris.cluster.ControllerService/{method}", self._proxy_rpc, methods=["POST"]),
             static_files_mount(),
         ]
-        return Starlette(routes=routes, on_shutdown=[self._client.aclose])
+
+        return Starlette(routes=routes, lifespan=on_shutdown(self._client.aclose))
 
     def _proxy_html(self, dashboard_type: str) -> HTMLResponse:
         html = html_shell("Iris Controller (Proxy)", dashboard_type)

lib/iris/src/iris/cluster/dashboard_common.py

@@ -9,16 +9,34 @@
 """
 
 import logging
+from collections.abc import AsyncGenerator, Awaitable, Callable
+from contextlib import AbstractAsyncContextManager, asynccontextmanager
 from pathlib import Path
 from typing import Any
 
+from starlette.applications import Starlette
 from starlette.responses import PlainTextResponse
 from starlette.routing import Mount
 from starlette.staticfiles import StaticFiles
 from starlette.types import ASGIApp, Receive, Scope, Send
 
 logger = logging.getLogger(__name__)
 
+
+def on_shutdown(
+    *callbacks: Callable[[], Awaitable[None]],
+) -> Callable[[Starlette], AbstractAsyncContextManager[None]]:
+    """Build a Starlette ``lifespan`` that runs *callbacks* on shutdown."""
+
+    @asynccontextmanager
+    async def _lifespan(_app: Starlette) -> AsyncGenerator[None, None]:
+        yield
+        for cb in callbacks:
+            await cb()
+
+    return _lifespan
+
+
 # Vue dashboard build output. The path from this file (cluster/dashboard_common.py)
 # up to lib/iris/ is four parent directories, then down into dashboard/dist.
 VUE_DIST_DIR = Path(__file__).parent.parent.parent.parent / "dashboard" / "dist"

lib/iris/tests/actor/test_actor_proxy.py

@@ -14,6 +14,7 @@
 from iris.actor import ActorClient, ActorServer
 from iris.actor.resolver import ACTOR_ENDPOINT_HEADER, ProxyResolver
 from iris.cluster.controller.actor_proxy import PROXY_ROUTE
+from iris.cluster.dashboard_common import on_shutdown
 from iris.managed_thread import ThreadContainer
 from iris.time_utils import Duration, ExponentialBackoff
 
@@ -109,7 +110,7 @@ def _start_proxy_server(proxy: StandaloneActorProxy, threads: ThreadContainer) -
 
     app = Starlette(
         routes=[Route(PROXY_ROUTE, proxy.handle, methods=["POST"])],
-        on_shutdown=[proxy.close],
+        lifespan=on_shutdown(proxy.close),
     )
     config = uvicorn.Config(app, host="127.0.0.1", port=port, log_level="error", log_config=None)
     server = uvicorn.Server(config)