Start the demo's services with the server

Building them at import allocated a room and a composition before startup, and
leaked the room when the composition failed.

Author: Gawor270

examples/composition/composition/app.py

@@ -1,3 +1,5 @@
+from contextlib import asynccontextmanager
+
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
 from starlette.middleware.cors import CORSMiddleware
@@ -9,41 +11,62 @@
 from .config import COMPOSITION_URL, FISHJAM_ID, FISHJAM_TOKEN
 from .fishjam_service import FishjamService
 
-fishjam = FishjamService(FISHJAM_ID, FISHJAM_TOKEN)
-composition = CompositionService(FISHJAM_TOKEN, COMPOSITION_URL)
-
-
-def start_composing() -> None:
-    composition.register_assets()
-    composition.play_movie()
-    composition.camera()
-    composition.stream_to(
-        fishjam.livestream_whip_url(), fishjam.create_streamer_token()
-    )
 
+def clean_up(*services) -> None:
+    for service in services:
+        if service is None:
+            continue
 
-def cleanup() -> None:
-    for service in (composition, fishjam):
         try:
             service.cleanup()
         except Exception as error:
             print(f"cleanup failed: {error}")
 
 
-async def streamer(_request: Request) -> Response:
-    camera = composition.camera()
+@asynccontextmanager
+async def lifespan(app: Starlette):
+    fishjam = composition = None
+
+    try:
+        fishjam = FishjamService(FISHJAM_ID, FISHJAM_TOKEN)
+        composition = CompositionService(FISHJAM_TOKEN, COMPOSITION_URL)
+        composition.register_assets()
+        composition.play_movie()
+        composition.camera()
+        composition.stream_to(
+            fishjam.livestream_whip_url(), fishjam.create_streamer_token()
+        )
+    except Exception:
+        clean_up(composition, fishjam)
+        raise
+
+    app.state.fishjam = fishjam
+    app.state.composition = composition
+
+    try:
+        yield
+    finally:
+        clean_up(composition, fishjam)
+        print("deleted the composition and the livestream room")
+
+
+async def streamer(request: Request) -> Response:
+    camera = request.app.state.composition.camera()
 
     return JSONResponse({"url": camera.url, "token": camera.bearer_token})
 
 
-async def viewer(_request: Request) -> Response:
+async def viewer(request: Request) -> Response:
+    fishjam = request.app.state.fishjam
+
     return JSONResponse({
         "url": fishjam.livestream_whep_url(),
         "token": fishjam.create_viewer_token(),
     })
 
 
 app = Starlette(
+    lifespan=lifespan,
     routes=[
         Route("/streamer", streamer, methods=["GET"]),
         Route("/viewer", viewer, methods=["GET"]),

examples/composition/main.py

@@ -1,32 +1,8 @@
-import sys
-from contextlib import asynccontextmanager
-
 import uvicorn
-from composition.app import app, cleanup, start_composing
+from composition.app import app
 from composition.config import HOST, PORT
 
-
-@asynccontextmanager
-async def lifespan(_app):
-    try:
-        start_composing()
-    except Exception as error:
-        print(f"failed to start composing: {error}", file=sys.stderr)
-        cleanup()
-        raise SystemExit(1) from error
-
+if __name__ == "__main__":
     print(f"streamer credentials on http://{HOST}:{PORT}/streamer")
     print(f"viewer token on http://{HOST}:{PORT}/viewer")
-
-    try:
-        yield
-    finally:
-        cleanup()
-        print("deleted the composition and the livestream room")
-
-
-app.router.lifespan_context = lifespan
-
-
-if __name__ == "__main__":
     uvicorn.run(app, host=HOST, port=PORT, log_level="info")