fix: use lifespan instead of on_startup/on_shutdown for Starlette 1.0 compatibility

Starlette 1.0 removed the on_startup and on_shutdown parameters in favor
of the lifespan context manager. This change migrates to using lifespan,
which has been supported since Starlette 0.13.5.

Fixes #1143

Author: Maarten Breddels AI

solara/server/starlette.py

@@ -1,4 +1,5 @@
 import asyncio
+from contextlib import asynccontextmanager
 import json
 import logging
 import math
@@ -633,6 +634,14 @@ def on_shutdown():
     telemetry.server_stop()
 
 
+@asynccontextmanager
+async def lifespan(app):
+    """Lifespan context manager for Starlette (replaces on_startup/on_shutdown)."""
+    on_startup()
+    yield
+    on_shutdown()
+
+
 def readyz(request: Request):
     json, status = server.readyz()
     return JSONResponse(json, status_code=status)
@@ -767,7 +776,7 @@ def expand(named_tuple):
     Route("/{fullpath:path}", endpoint=root),
 ]
 
-app = Starlette(routes=routes, on_startup=[on_startup], on_shutdown=[on_shutdown], middleware=middleware)
+app = Starlette(routes=routes, lifespan=lifespan, middleware=middleware)
 
 # Uncomment the lines below to test solara mouted under a subpath
 # def myroot(request: Request):

tests/unit/starlette_lifespan_test.py

@@ -0,0 +1,23 @@
+"""Tests for Starlette lifespan context manager."""
+
+import asyncio
+from unittest import mock
+
+
+def test_lifespan_context_manager():
+    """Test that the lifespan context manager calls on_startup and on_shutdown."""
+    from solara.server.starlette import lifespan
+
+    startup_called = []
+    shutdown_called = []
+
+    with mock.patch("solara.server.starlette.on_startup", lambda: startup_called.append(True)):
+        with mock.patch("solara.server.starlette.on_shutdown", lambda: shutdown_called.append(True)):
+
+            async def test_lifespan():
+                async with lifespan(None):
+                    assert startup_called == [True], "on_startup should be called before yield"
+                    assert shutdown_called == [], "on_shutdown should not be called before yield"
+                assert shutdown_called == [True], "on_shutdown should be called after yield"
+
+            asyncio.run(test_lifespan())