refactor: use new fastapi lifespan instead of startup/shutdown events (#2294)

* refactor: use new fastapi lifespan instead of events
recommended use: https://fastapi.tiangolo.com/advanced/events/?h=lifespan
threw warnings in pytest
* make startup and shutdown functions
* nix: add override for asgi-lifespan

---------

Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

lnbits/app.py

@@ -7,6 +7,7 @@ import shutil
 import signal
 import sys
 import traceback
+from contextlib import asynccontextmanager
 from hashlib import sha256
 from http import HTTPStatus
 from pathlib import Path
@@ -68,6 +69,59 @@ from .tasks import (
 )
 
 
+async def startup(app: FastAPI):
+
+    # wait till migration is done
+    await migrate_databases()
+
+    # setup admin settings
+    await check_admin_settings()
+    await check_webpush_settings()
+
+    log_server_info()
+
+    # initialize WALLET
+    try:
+        set_wallet_class()
+    except Exception as e:
+        logger.error(f"Error initializing {settings.lnbits_backend_wallet_class}: {e}")
+        set_void_wallet_class()
+
+    # initialize funding source
+    await check_funding_source()
+
+    # register core routes
+    init_core_routers(app)
+
+    # check extensions after restart
+    if not settings.lnbits_extensions_deactivate_all:
+        await check_installed_extensions(app)
+        register_all_ext_routes(app)
+
+    if settings.lnbits_admin_ui:
+        initialize_server_logger()
+
+    # initialize tasks
+    register_async_tasks()
+
+
+async def shutdown():
+    # shutdown event
+    cancel_all_tasks()
+
+    # wait a bit to allow them to finish, so that cleanup can run without problems
+    await asyncio.sleep(0.1)
+    WALLET = get_wallet_class()
+    await WALLET.cleanup()
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    await startup(app)
+    yield
+    await shutdown()
+
+
 def create_app() -> FastAPI:
     configure_logger()
     app = FastAPI(
@@ -77,6 +131,7 @@ def create_app() -> FastAPI:
             "accounts system with plugins."
         ),
         version=settings.version,
+        lifespan=lifespan,
         license_info={
             "name": "MIT License",
             "url": "https://raw.githubusercontent.com/lnbits/lnbits/main/LICENSE",
@@ -117,10 +172,7 @@ def create_app() -> FastAPI:
     add_ip_block_middleware(app)
     add_ratelimit_middleware(app)
 
-    register_startup(app)
-    register_async_tasks(app)
     register_exception_handlers(app)
-    register_shutdown(app)
 
     return app
 
@@ -368,56 +420,6 @@ def register_all_ext_routes(app: FastAPI):
             logger.error(f"Could not load extension `{ext.code}`: {str(e)}")
 
 
-def register_startup(app: FastAPI):
-    @app.on_event("startup")
-    async def lnbits_startup():
-        try:
-            # wait till migration is done
-            await migrate_databases()
-
-            # setup admin settings
-            await check_admin_settings()
-            await check_webpush_settings()
-
-            log_server_info()
-
-            # initialize WALLET
-            try:
-                set_wallet_class()
-            except Exception as e:
-                logger.error(
-                    f"Error initializing {settings.lnbits_backend_wallet_class}: {e}"
-                )
-                set_void_wallet_class()
-
-            # initialize funding source
-            await check_funding_source()
-
-            init_core_routers(app)
-
-            # check extensions after restart
-            if not settings.lnbits_extensions_deactivate_all:
-                await check_installed_extensions(app)
-                register_all_ext_routes(app)
-
-            if settings.lnbits_admin_ui:
-                initialize_server_logger()
-
-        except Exception as e:
-            logger.error(str(e))
-            raise ImportError("Failed to run 'startup' event.")
-
-
-def register_shutdown(app: FastAPI):
-    @app.on_event("shutdown")
-    async def on_shutdown():
-        cancel_all_tasks()
-        # wait a bit to allow them to finish, so that cleanup can run without problems
-        await asyncio.sleep(0.1)
-        WALLET = get_wallet_class()
-        await WALLET.cleanup()
-
-
 def initialize_server_logger():
     super_user_hash = sha256(settings.super_user.encode("utf-8")).hexdigest()
 
@@ -465,22 +467,20 @@ def get_db_vendor_name():
     )
 
 
-def register_async_tasks(app):
-    @app.on_event("startup")
-    async def listeners():
-        create_permanent_task(check_pending_payments)
-        create_permanent_task(invoice_listener)
-        create_permanent_task(internal_invoice_listener)
-        create_permanent_task(cache.invalidate_forever)
+def register_async_tasks():
+    create_permanent_task(check_pending_payments)
+    create_permanent_task(invoice_listener)
+    create_permanent_task(internal_invoice_listener)
+    create_permanent_task(cache.invalidate_forever)
 
-        # core invoice listener
-        invoice_queue = asyncio.Queue(5)
-        register_invoice_listener(invoice_queue, "core")
-        create_permanent_task(lambda: wait_for_paid_invoices(invoice_queue))
+    # core invoice listener
+    invoice_queue = asyncio.Queue(5)
+    register_invoice_listener(invoice_queue, "core")
+    create_permanent_task(lambda: wait_for_paid_invoices(invoice_queue))
 
-        # TODO: implement watchdog properly
-        # create_permanent_task(watchdog_task)
-        create_permanent_task(killswitch_task)
+    # TODO: implement watchdog properly
+    # create_permanent_task(watchdog_task)
+    create_permanent_task(killswitch_task)
 
 
 def register_exception_handlers(app: FastAPI):