feat: Service.to_asgi() method

src/_bentoml_impl/worker/service.py

@@ -137,8 +137,6 @@ def main(
     from bentoml._internal.context import server_context
     from bentoml._internal.log import configure_server_logging
 
-    from ..server.app import ServiceAppFactory
-
     if runner_map:
         BentoMLContainer.remote_runner_mapping.set(
             t.cast(t.Dict[str, str], json.loads(runner_map))
@@ -163,9 +161,9 @@ def main(
         BentoMLContainer.prometheus_multiproc_dir.set(prometheus_dir)
     server_context.service_name = service.name
 
-    asgi_app = ServiceAppFactory(
-        service, is_main=server_context.service_type == "entry_service"
-    )()
+    asgi_app = service.to_asgi(
+        is_main=server_context.service_type == "entry_service", init=False
+    )
 
     uvicorn_extra_options: dict[str, t.Any] = {}
     if ssl_version is not None:

src/_bentoml_sdk/decorators.py

@@ -107,7 +107,7 @@ def wrapper(func: t.Callable[t.Concatenate[t.Any, P], R]) -> APIMethod[P, R]:
 
 def mount_asgi_app(
     app: ASGIApp, *, path: str = "/", name: str | None = None
-) -> t.Callable[[T], T]:
+) -> t.Callable[[R], R]:
     """Mount an ASGI app to the service.
 
     Args:
@@ -119,7 +119,7 @@ def mount_asgi_app(
     from ._internals import make_fastapi_class_views
     from .service import Service
 
-    def decorator(obj: T) -> T:
+    def decorator(obj: R) -> R:
         lazy_fastapi = LazyType["FastAPI"]("fastapi.FastAPI")
 
         if isinstance(obj, Service):

src/_bentoml_sdk/service/factory.py

@@ -198,6 +198,15 @@ def import_string(self) -> str:
                 )
         return self._import_str
 
+    def to_asgi(self, is_main: bool = True, init: bool = False) -> ext.ASGIApp:
+        from _bentoml_impl.server.app import ServiceAppFactory
+
+        self.inject_config()
+        factory = ServiceAppFactory(self, is_main=is_main)
+        if init:
+            factory.create_instance()
+        return factory()
+
     def mount_asgi_app(
         self, app: ext.ASGIApp, path: str = "/", name: str | None = None
     ) -> None:

tests/unit/bentoml_io/test_decorators.py

@@ -8,58 +8,40 @@ async def test_mount_asgi_app():
     import httpx
     from fastapi import FastAPI
 
-    from _bentoml_impl.server.app import ServiceAppFactory
-
     app = FastAPI()
 
     @bentoml.mount_asgi_app(app, path="/test")
-    @bentoml.service
+    @bentoml.service(metrics={"enabled": False})
     class TestService:
         @app.get("/hello")
         def hello(self):
             return {"message": "Hello, world!"}
 
-    TestService.inject_config()
-
-    factory = ServiceAppFactory(TestService, is_main=True, enable_metrics=False)
-    factory.create_instance()
-    try:
-        async with httpx.AsyncClient(
-            app=factory(), base_url="http://testserver"
-        ) as client:
-            response = await client.get("/test/hello")
-            assert response.status_code == 200
-            assert response.json()["message"] == "Hello, world!"
-    finally:
-        await factory.destroy_instance()
+    async with httpx.AsyncClient(
+        app=TestService.to_asgi(init=True), base_url="http://testserver"
+    ) as client:
+        response = await client.get("/test/hello")
+        assert response.status_code == 200
+        assert response.json()["message"] == "Hello, world!"
 
 
 @pytest.mark.asyncio
 async def test_mount_asgi_app_later():
     import httpx
     from fastapi import FastAPI
 
-    from _bentoml_impl.server.app import ServiceAppFactory
-
     app = FastAPI()
 
-    @bentoml.service
+    @bentoml.service(metrics={"enabled": False})
     @bentoml.mount_asgi_app(app, path="/test")
     class TestService:
         @app.get("/hello")
         def hello(self):
             return {"message": "Hello, world!"}
 
-    TestService.inject_config()
-
-    factory = ServiceAppFactory(TestService, is_main=True, enable_metrics=False)
-    factory.create_instance()
-    try:
-        async with httpx.AsyncClient(
-            app=factory(), base_url="http://testserver"
-        ) as client:
-            response = await client.get("/test/hello")
-            assert response.status_code == 200
-            assert response.json()["message"] == "Hello, world!"
-    finally:
-        await factory.destroy_instance()
+    async with httpx.AsyncClient(
+        app=TestService.to_asgi(init=True), base_url="http://testserver"
+    ) as client:
+        response = await client.get("/test/hello")
+        assert response.status_code == 200
+        assert response.json()["message"] == "Hello, world!"