feat(framework) Add FAB hash to load_client_app_fn (#4305)

src/py/flwr/cli/install.py

@@ -164,9 +164,7 @@ def validate_and_install(
     install_dir: Path = (
         (get_flwr_dir() if not flwr_dir else flwr_dir)
         / "apps"
-        / publisher
-        / project_name
-        / version
+        / f"{publisher}.{project_name}.{version}.{fab_hash[:FAB_HASH_TRUNCATION]}"
     )
     if install_dir.exists():
         if skip_prompt:

src/py/flwr/client/app.py

@@ -202,7 +202,7 @@ def start_client_internal(
     *,
     server_address: str,
     node_config: UserConfig,
-    load_client_app_fn: Optional[Callable[[str, str], ClientApp]] = None,
+    load_client_app_fn: Optional[Callable[[str, str, str], ClientApp]] = None,
     client_fn: Optional[ClientFnExt] = None,
     client: Optional[Client] = None,
     grpc_max_message_length: int = GRPC_MAX_MESSAGE_LENGTH,
@@ -298,7 +298,7 @@ def single_client_factory(
 
             client_fn = single_client_factory
 
-        def _load_client_app(_1: str, _2: str) -> ClientApp:
+        def _load_client_app(_1: str, _2: str, _3: str) -> ClientApp:
             return ClientApp(client_fn=client_fn)
 
         load_client_app_fn = _load_client_app
@@ -529,7 +529,7 @@ def _on_backoff(retry_state: RetryState) -> None:
                         else:
                             # Load ClientApp instance
                             client_app: ClientApp = load_client_app_fn(
-                                fab_id, fab_version
+                                fab_id, fab_version, run.fab_hash
                             )
 
                             # Execute ClientApp

src/py/flwr/client/clientapp/app.py

@@ -132,8 +132,11 @@ def run_clientapp(  # pylint: disable=R0914
             )
 
             try:
-                # Load ClientApp
-                client_app: ClientApp = load_client_app_fn(run.fab_id, run.fab_version)
+                if fab:
+                    # Load ClientApp
+                    client_app: ClientApp = load_client_app_fn(
+                        run.fab_id, run.fab_version, fab.hash_str
+                    )
 
                 # Execute ClientApp
                 reply_message = client_app(message=message, context=context)

src/py/flwr/client/clientapp/utils.py

@@ -34,7 +34,7 @@ def get_load_client_app_fn(
     app_path: Optional[str],
     multi_app: bool,
     flwr_dir: Optional[str] = None,
-) -> Callable[[str, str], ClientApp]:
+) -> Callable[[str, str, str], ClientApp]:
     """Get the load_client_app_fn function.
 
     If `multi_app` is True, this function loads the specified ClientApp
@@ -55,13 +55,14 @@ def get_load_client_app_fn(
         if not valid and error_msg:
             raise LoadClientAppError(error_msg) from None
 
-    def _load(fab_id: str, fab_version: str) -> ClientApp:
+    def _load(fab_id: str, fab_version: str, fab_hash: str) -> ClientApp:
         runtime_app_dir = Path(app_path if app_path else "").absolute()
         # If multi-app feature is disabled
         if not multi_app:
             # Set app reference
             client_app_ref = default_app_ref
-        # If multi-app feature is enabled but app directory is provided
+        # If multi-app feature is enabled but app directory is provided.
+        # `fab_hash` is not required since the app is loaded from `runtime_app_dir`.
         elif app_path is not None:
             config = get_project_config(runtime_app_dir)
             this_fab_version, this_fab_id = get_metadata_from_config(config)
@@ -81,11 +82,16 @@ def _load(fab_id: str, fab_version: str) -> ClientApp:
         else:
             try:
                 runtime_app_dir = get_project_dir(
-                    fab_id, fab_version, get_flwr_dir(flwr_dir)
+                    fab_id, fab_version, fab_hash, get_flwr_dir(flwr_dir)
                 )
                 config = get_project_config(runtime_app_dir)
             except Exception as e:
-                raise LoadClientAppError("Failed to load ClientApp") from e
+                raise LoadClientAppError(
+                    "Failed to load ClientApp."
+                    "Possible reasons for error include mismatched "
+                    "`fab_id`, `fab_version`, or `fab_hash` in "
+                    f"{str(get_flwr_dir(flwr_dir).resolve())}."
+                ) from e
 
             # Set app reference
             client_app_ref = config["tool"]["flwr"]["app"]["components"]["clientapp"]

src/py/flwr/common/config.py

@@ -22,7 +22,12 @@
 import tomli
 
 from flwr.cli.config_utils import get_fab_config, validate_fields
-from flwr.common.constant import APP_DIR, FAB_CONFIG_FILE, FLWR_HOME
+from flwr.common.constant import (
+    APP_DIR,
+    FAB_CONFIG_FILE,
+    FAB_HASH_TRUNCATION,
+    FLWR_HOME,
+)
 from flwr.common.typing import Run, UserConfig, UserConfigValue
 
 
@@ -39,7 +44,10 @@ def get_flwr_dir(provided_path: Optional[str] = None) -> Path:
 
 
 def get_project_dir(
-    fab_id: str, fab_version: str, flwr_dir: Optional[Union[str, Path]] = None
+    fab_id: str,
+    fab_version: str,
+    fab_hash: str,
+    flwr_dir: Optional[Union[str, Path]] = None,
 ) -> Path:
     """Return the project directory based on the given fab_id and fab_version."""
     # Check the fab_id
@@ -50,7 +58,11 @@ def get_project_dir(
     publisher, project_name = fab_id.split("/")
     if flwr_dir is None:
         flwr_dir = get_flwr_dir()
-    return Path(flwr_dir) / APP_DIR / publisher / project_name / fab_version
+    return (
+        Path(flwr_dir)
+        / APP_DIR
+        / f"{publisher}.{project_name}.{fab_version}.{fab_hash[:FAB_HASH_TRUNCATION]}"
+    )
 
 
 def get_project_config(project_dir: Union[str, Path]) -> dict[str, Any]:
@@ -127,7 +139,7 @@ def get_fused_config(run: Run, flwr_dir: Optional[Path]) -> UserConfig:
     if not run.fab_id or not run.fab_version:
         return {}
 
-    project_dir = get_project_dir(run.fab_id, run.fab_version, flwr_dir)
+    project_dir = get_project_dir(run.fab_id, run.fab_version, run.fab_hash, flwr_dir)
 
     # Return empty dict if project directory does not exist
     if not project_dir.is_dir():

src/py/flwr/common/config_test.py

@@ -65,13 +65,22 @@ def test_get_flwr_dir_with_xdg_data_home() -> None:
 def test_get_project_dir_invalid_fab_id() -> None:
     """Test get_project_dir with an invalid fab_id."""
     with pytest.raises(ValueError):
-        get_project_dir("invalid_fab_id", "1.0.0")
+        get_project_dir(
+            "invalid_fab_id",
+            "1.0.0",
+            "03840e932bf61247c1231f0aec9e8ec5f041ed5516fb23638f24d25f3a007acd",
+        )
 
 
 def test_get_project_dir_valid() -> None:
     """Test get_project_dir with an valid fab_id and version."""
-    app_path = get_project_dir("app_name/user", "1.0.0", flwr_dir=".")
-    assert app_path == Path("apps") / "app_name" / "user" / "1.0.0"
+    app_path = get_project_dir(
+        "app_name/user",
+        "1.0.0",
+        "03840e932bf61247c1231f0aec9e8ec5f041ed5516fb23638f24d25f3a007acd",
+        flwr_dir=".",
+    )
+    assert app_path == Path("apps") / "app_name.user.1.0.0.03840e93"
 
 
 def test_get_project_config_file_not_found() -> None:

src/py/flwr/server/run_serverapp.py

@@ -181,19 +181,17 @@ def run_server_app() -> None:
         )
         flwr_dir = get_flwr_dir(args.flwr_dir)
         run_ = driver.run
-        if run_.fab_hash:
-            fab_req = GetFabRequest(hash_str=run_.fab_hash)
-            # pylint: disable-next=W0212
-            fab_res: GetFabResponse = driver._stub.GetFab(fab_req)
-            if fab_res.fab.hash_str != run_.fab_hash:
-                raise ValueError("FAB hashes don't match.")
-
-            install_from_fab(fab_res.fab.content, flwr_dir, True)
-            fab_id, fab_version = get_fab_metadata(fab_res.fab.content)
-        else:
-            fab_id, fab_version = run_.fab_id, run_.fab_version
-
-        app_path = str(get_project_dir(fab_id, fab_version, flwr_dir))
+        if not run_.fab_hash:
+            raise ValueError("FAB hash not provided.")
+        fab_req = GetFabRequest(hash_str=run_.fab_hash)
+        # pylint: disable-next=W0212
+        fab_res: GetFabResponse = driver._stub.GetFab(fab_req)
+        if fab_res.fab.hash_str != run_.fab_hash:
+            raise ValueError("FAB hashes don't match.")
+        install_from_fab(fab_res.fab.content, flwr_dir, True)
+        fab_id, fab_version = get_fab_metadata(fab_res.fab.content)
+
+        app_path = str(get_project_dir(fab_id, fab_version, run_.fab_hash, flwr_dir))
         config = get_project_config(app_path)
     else:
         # User provided `app_dir`, but not `--run-id`

src/py/flwr/server/superlink/fleet/vce/vce_api.py

@@ -346,7 +346,7 @@ def _load() -> ClientApp:
                 app_path=app_dir,
                 flwr_dir=flwr_dir,
                 multi_app=False,
-            )(run.fab_id, run.fab_version)
+            )(run.fab_id, run.fab_version, run.fab_hash)
 
         if client_app:
             app = client_app