feat(framework) Enable configuring the simulation backend via flwr run

src/py/flwr/cli/run/run.py

@@ -15,6 +15,7 @@
 """Flower command line interface `run` command."""
 
 import hashlib
+import json
 import subprocess
 import sys
 from logging import DEBUG
@@ -192,6 +193,8 @@ def _run_without_superexec(
 ) -> None:
     try:
         num_supernodes = federation_config["options"]["num-supernodes"]
+        verbose: Optional[bool] = federation_config["options"].get("verbose")
+        backend_cfg = federation_config["options"].get("backend", {})
     except KeyError as err:
         typer.secho(
             "❌ The project's `pyproject.toml` needs to declare the number of"
@@ -212,6 +215,13 @@ def _run_without_superexec(
         f"{num_supernodes}",
     ]
 
+    if backend_cfg:
+        # Stringify as JSON
+        command.extend(["--backend-config", json.dumps(backend_cfg)])
+
+    if verbose:
+        command.extend(["--verbose"])
+
     if config_overrides:
         command.extend(["--run-config", f"{' '.join(config_overrides)}"])
 

src/py/flwr/simulation/run_simulation.py

@@ -25,7 +25,7 @@
 from logging import DEBUG, ERROR, INFO, WARNING
 from pathlib import Path
 from time import sleep
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from flwr.cli.config_utils import load_and_validate
 from flwr.client import ClientApp
@@ -91,6 +91,17 @@ def _resolve_message(conflict_keys: List[str]) -> str:
     return True
 
 
+def _replace_keys(d: Any, match: str, target: str) -> Any:
+    if isinstance(d, dict):
+        return {
+            k.replace(match, target): _replace_keys(v, match, target)
+            for k, v in d.items()
+        }
+    if isinstance(d, list):
+        return [_replace_keys(i, match, target) for i in d]
+    return d
+
+
 # Entry point from CLI
 # pylint: disable=too-many-locals
 def run_simulation_from_cli() -> None:
@@ -105,6 +116,14 @@ def run_simulation_from_cli() -> None:
             code_example='TF_FORCE_GPU_ALLOW_GROWTH="true" flower-simulation <...>',
         )
 
+    # Load JSON config
+    backend_config_dict = json.loads(args.backend_config)
+
+    if backend_config_dict:
+        # Backend config internally operates with `_` not with `-`
+        backend_config_dict = _replace_keys(backend_config_dict, match="-", target="_")
+        log(DEBUG, "backend_config_dict: %s", backend_config_dict)
+
     # We are supporting two modes for the CLI entrypoint:
     # 1) Running an app dir containing a `pyproject.toml`
     # 2) Running any ClientApp and SeverApp w/o pyproject.toml being present
@@ -167,9 +186,6 @@ def run_simulation_from_cli() -> None:
         override_config=override_config,
     )
 
-    # Load JSON config
-    backend_config_dict = json.loads(args.backend_config)
-
     _run_simulation(
         server_app_attr=server_app_attr,
         client_app_attr=client_app_attr,

src/py/flwr/superexec/simulation.py

@@ -15,6 +15,7 @@
 """Simulation engine executor."""
 
 
+import json
 import subprocess
 import sys
 from logging import ERROR, INFO, WARN
@@ -24,6 +25,7 @@
 
 from flwr.cli.config_utils import load_and_validate
 from flwr.cli.install import install_from_fab
+from flwr.common.config import unflatten_dict
 from flwr.common.constant import RUN_ID_NUM_BYTES
 from flwr.common.logger import log
 from flwr.common.typing import UserConfig
@@ -108,6 +110,7 @@ def set_config(
                 )
             self.verbose = verbose
 
+    # pylint: disable=too-many-locals
     @override
     def start_run(
         self,
@@ -152,6 +155,15 @@ def start_run(
                     "Config extracted from FAB's pyproject.toml is not valid"
                 )
 
+            # Flatten federated config
+            federation_config_flat = unflatten_dict(federation_config)
+
+            num_supernodes = federation_config_flat.get(
+                "num-supernodes", self.num_supernodes
+            )
+            backend_cfg = federation_config_flat.get("backend", {})
+            verbose: Optional[bool] = federation_config_flat.get("verbose")
+
             # In Simulation there is no SuperLink, still we create a run_id
             run_id = generate_rand_int_from_bytes(RUN_ID_NUM_BYTES)
             log(INFO, "Created run %s", str(run_id))
@@ -162,11 +174,18 @@ def start_run(
                 "--app",
                 f"{str(fab_path)}",
                 "--num-supernodes",
-                f"{federation_config.get('num-supernodes', self.num_supernodes)}",
+                f"{num_supernodes}",
                 "--run-id",
                 str(run_id),
             ]
 
+            if backend_cfg:
+                # Stringify as JSON
+                command.extend(["--backend-config", json.dumps(backend_cfg)])
+
+            if verbose:
+                command.extend(["--verbose"])
+
             if override_config:
                 override_config_str = _user_config_to_str(override_config)
                 command.extend(["--run-config", f"{override_config_str}"])