feat(framework) Add internal flwr-clientapp command (#3973)

Co-authored-by: Daniel J. Beutel <[email protected]>

pyproject.toml

@@ -59,6 +59,7 @@ flower-supernode = "flwr.client:run_supernode"
 flower-client-app = "flwr.client:run_client_app"
 flower-server-app = "flwr.server:run_server_app"
 flower-simulation = "flwr.simulation.run_simulation:run_simulation_from_cli"
+flwr-clientapp = "flwr.client.supernode:flwr_clientapp"
 
 [tool.poetry.dependencies]
 python = "^3.8"

src/py/flwr/client/supernode/__init__.py

@@ -15,10 +15,12 @@
 """Flower SuperNode."""
 
 
+from .app import flwr_clientapp as flwr_clientapp
 from .app import run_client_app as run_client_app
 from .app import run_supernode as run_supernode
 
 __all__ = [
+    "flwr_clientapp",
     "run_client_app",
     "run_supernode",
 ]

src/py/flwr/client/supernode/app.py

@@ -120,6 +120,31 @@ def run_client_app() -> None:
     register_exit_handlers(event_type=EventType.RUN_CLIENT_APP_LEAVE)
 
 
+def flwr_clientapp() -> None:
+    """Run process-isolated Flower ClientApp."""
+    log(INFO, "Starting Flower ClientApp")
+
+    parser = argparse.ArgumentParser(
+        description="Run a Flower ClientApp",
+    )
+    parser.add_argument(
+        "--address",
+        help="Address of SuperNode ClientAppIo gRPC servicer",
+    )
+    parser.add_argument(
+        "--token",
+        help="Unique token generated by SuperNode for each ClientApp execution",
+    )
+    args = parser.parse_args()
+    log(
+        DEBUG,
+        "Staring isolated `ClientApp` connected to SuperNode ClientAppIo at %s "
+        "with the token %s",
+        args.address,
+        args.token,
+    )
+
+
 def _warn_deprecated_server_arg(args: argparse.Namespace) -> None:
     """Warn about the deprecated argument `--server`."""
     if args.server != ADDRESS_FLEET_API_GRPC_RERE: