Remove app_module_for_backend

* Replace app_module_for_backend with ASGI factory on `rx.App.__call__`
* Consolidate module spec for uvicorn, gunicorn, and granian

reflex/app.py

@@ -468,6 +468,22 @@ class App(MiddlewareMixin, LifespanMixin):
         """
         if not self.api:
             raise ValueError("The app has not been initialized.")
+
+        # For py3.9 compatibility when redis is used, we MUST add any decorator pages
+        # before compiling the app in a thread to avoid event loop error (REF-2172).
+        self._apply_decorated_pages()
+
+        compile_future = concurrent.futures.ThreadPoolExecutor(max_workers=1).submit(
+            self._compile
+        )
+        compile_future.add_done_callback(
+            # Force background compile errors to print eagerly
+            lambda f: f.result()
+        )
+        # Wait for the compile to finish in prod mode to ensure all optional endpoints are mounted.
+        if is_prod_mode():
+            compile_future.result()
+
         return self.api
 
     def _add_default_endpoints(self):

reflex/app_module_for_backend.py

@@ -1,33 +0,0 @@
-"""Shims the real reflex app module for running backend server (uvicorn or gunicorn).
-Only the app attribute is explicitly exposed.
-"""
-
-from concurrent.futures import ThreadPoolExecutor
-
-from reflex import constants
-from reflex.utils.exec import is_prod_mode
-from reflex.utils.prerequisites import get_and_validate_app
-
-if constants.CompileVars.APP != "app":
-    raise AssertionError("unexpected variable name for 'app'")
-
-app, app_module = get_and_validate_app(reload=False)
-# For py3.9 compatibility when redis is used, we MUST add any decorator pages
-# before compiling the app in a thread to avoid event loop error (REF-2172).
-app._apply_decorated_pages()
-compile_future = ThreadPoolExecutor(max_workers=1).submit(app._compile)
-compile_future.add_done_callback(
-    # Force background compile errors to print eagerly
-    lambda f: f.result()
-)
-# Wait for the compile to finish in prod mode to ensure all optional endpoints are mounted.
-if is_prod_mode():
-    compile_future.result()
-
-# ensure only "app" is exposed.
-del app_module
-del compile_future
-del get_and_validate_app
-del is_prod_mode
-del constants
-del ThreadPoolExecutor

reflex/utils/exec.py

@@ -195,22 +195,9 @@ def get_app_module():
     Returns:
         The app module for the backend.
     """
-    return f"reflex.app_module_for_backend:{constants.CompileVars.APP}"
+    config = get_config()
 
-
-def get_granian_target():
-    """Get the Granian target for the backend.
-
-    Returns:
-        The Granian target for the backend.
-    """
-    import reflex
-
-    app_module_path = Path(reflex.__file__).parent / "app_module_for_backend.py"
-
-    return (
-        f"{app_module_path!s}:{constants.CompileVars.APP}.{constants.CompileVars.API}"
-    )
+    return f"{config.module}:{constants.CompileVars.APP}"
 
 
 def run_backend(
@@ -278,7 +265,8 @@ def run_uvicorn_backend(host: str, port: int, loglevel: LogLevel):
     import uvicorn
 
     uvicorn.run(
-        app=f"{get_app_module()}.{constants.CompileVars.API}",
+        app=f"{get_app_module()}",
+        factory=True,
         host=host,
         port=port,
         log_level=loglevel.value,
@@ -304,7 +292,8 @@ def run_granian_backend(host: str, port: int, loglevel: LogLevel):
         from granian.log import LogLevels  # pyright: ignore [reportMissingImports]
 
         Granian(
-            target=get_granian_target(),
+            target=get_app_module(),
+            factory=True,
             address=host,
             port=port,
             interface=Interfaces.ASGI,
@@ -377,6 +366,7 @@ def run_uvicorn_backend_prod(host: str, port: int, loglevel: LogLevel):
             host,
             "--port",
             str(port),
+            "--factory",
             app_module,
         ]
         if constants.IS_WINDOWS
@@ -433,7 +423,8 @@ def run_granian_backend_prod(host: str, port: int, loglevel: LogLevel):
             str(port),
             "--interface",
             str(Interfaces.ASGI),
-            get_granian_target(),
+            "--factory",
+            get_app_module(),
         ]
         processes.new_process(
             command,