refactor(framework) Update CLI SSL flags

doc/source/how-to-authenticate-supernodes.rst

@@ -28,7 +28,9 @@ Use the following terminal command to start a Flower :code:`SuperNode` that has
 .. code-block:: bash
 
     flower-superlink
-        --certificates certificates/ca.crt certificates/server.pem certificates/server.key
+        --ssl-ca-certfile certificates/ca.crt 
+        --ssl-certfile certificates/server.pem 
+        --ssl-keyfile certificates/server.key
         --auth-list-public-keys keys/client_public_keys.csv
         --auth-superlink-private-key keys/server_credentials
         --auth-superlink-public-key keys/server_credentials.pub

doc/source/how-to-enable-ssl-connections.rst

@@ -42,7 +42,10 @@ Use the following terminal command to start a sever (SuperLink) that uses the pr
 
 .. code-block:: bash
 
-    flower-superlink --certificates certificates/ca.crt certificates/server.pem certificates/server.key
+    flower-superlink 
+      --ssl-ca-certfile certificates/ca.crt 
+      --ssl-certfile certificates/server.pem 
+      --ssl-keyfile certificates/server.key
 
 When providing certificates, the server expects a tuple of three certificates paths: CA certificate, server certificate and server private key.
 

doc/source/how-to-run-flower-using-docker.rst

@@ -102,13 +102,15 @@ PEM-encoded certificate chain.
 Assuming all files we need are in the local ``certificates`` directory, we can use the flag
 ``--volume`` to mount the local directory into the ``/app/`` directory of the container. This allows
 the SuperLink to access the files within the container. Finally, we pass the names of the
-certificates to the SuperLink with the ``--certificates`` flag.
+certificates to the SuperLink with the ``--root-certificates`` flag.
 
 .. code-block:: bash
 
   $ docker run --rm \
-    -p 9091:9091 -p 9092:9092 --volume ./certificates/:/app/ flwr/superlink:1.8.0 \
-    --certificates ca.crt server.pem server.key
+    -p 9091:9091 -p 9092:9092 --volume ./certificates/:/app/ flwr/superlink:1.9.0 \
+    --ssl-ca-certfile ca.crt \
+    --ssl-certfile server.pem \
+    --ssl-keyfile server.key
 
 Flower SuperNode
 ----------------
@@ -264,13 +266,13 @@ To enable SSL, we will need to mount a PEM-encoded root certificate into your Su
 
 Assuming the certificate already exists locally, we can use the flag ``--volume`` to mount the local
 certificate into the container's ``/app/`` directory. This allows the SuperNode to access the
-certificate within the container. Use the ``--certificates`` flag when starting the container.
+certificate within the container. Use the ``--root-certificates`` flag when starting the container.
 
 .. code-block:: bash
 
   $ docker run --rm --volume ./ca.crt:/app/ca.crt flwr_supernode:0.0.1 \
     --server 192.168.1.100:9092 \
-    --certificates ca.crt
+    --root-certificates ca.crt
 
 Flower ServerApp
 ----------------
@@ -379,13 +381,14 @@ To enable SSL, we will need to mount a PEM-encoded root certificate into your Se
 
 Assuming the certificate already exists locally, we can use the flag ``--volume`` to mount the local
 certificate into the container's ``/app/`` directory. This allows the ServerApp to access the
-certificate within the container. Use the ``--certificates`` flag when starting the container.
+certificate within the container. Use the ``--ssl-ca-certfile``, ``--ssl-certfile``, and ``--ssl-keyfile`` 
+flags when starting the container.
 
 .. code-block:: bash
 
   $ docker run --rm --volume ./ca.crt:/app/ca.crt flwr_serverapp:0.0.1 \
     --server 192.168.1.100:9091 \
-    --certificates ca.crt
+    --root-certificates ca.crt
 
 Advanced Docker options
 -----------------------

doc/source/how-to-upgrade-to-flower-next.rst

@@ -171,16 +171,16 @@ Deployment
     # In yet another terminal window, run the ServerApp (this starts the actual training run)
     $ flower-server-app server:app --insecure
 
-- Here's another example to start with HTTPS. Use the ``--certificates`` command line
-  argument to pass paths to (CA certificate, server certificate, and server private key).
+- Here's another example to start with HTTPS. Use the ``--ssl-ca-certfile``, ``--ssl-certfile``, and ``--ssl-keyfile`` command line
+  options to pass paths to (CA certificate, server certificate, and server private key).
 
 .. code-block:: bash
 
     # Start a secure Superlink
-    $ flower-superlink --certificates \
-        <your-ca-cert-filepath> \
-        <your-server-cert-filepath> \
-        <your-privatekey-filepath>
+    $ flower-superlink \
+        --ssl-ca-certfile <your-ca-cert-filepath> \
+        --ssl-certfile <your-server-cert-filepath> \
+        --ssl-keyfile <your-privatekey-filepath>
 
     # In a new terminal window, start a long-running secure SuperNode
     $ flower-client-app client:app \

e2e/test_driver.sh

@@ -9,7 +9,7 @@ case "$1" in
     ;;
   bare-https)
     ./generate.sh
-    server_arg="--certificates certificates/ca.crt certificates/server.pem certificates/server.key"
+    server_arg="--ssl-ca-certfile certificates/ca.crt --ssl-certfile certificates/server.pem --ssl-keyfile certificates/server.key"
     client_arg="--root-certificates certificates/ca.crt"
     server_dir="./"
     ;;
@@ -45,7 +45,7 @@ case "$2" in
     server_address="127.0.0.1:9092"
     server_app_address="127.0.0.1:9091"
     db_arg="--database :flwr-in-memory-state:"
-    server_arg="--certificates certificates/ca.crt certificates/server.pem certificates/server.key"
+    server_arg="--ssl-ca-certfile certificates/ca.crt --ssl-certfile certificates/server.pem --ssl-keyfile certificates/server.key"
     client_arg="--root-certificates certificates/ca.crt"
     server_auth="--auth-list-public-keys keys/client_public_keys.csv --auth-superlink-private-key keys/server_credentials --auth-superlink-public-key keys/server_credentials.pub"
     client_auth_1="--auth-supernode-private-key keys/client_credentials_1 --auth-supernode-public-key keys/client_credentials_1.pub"

examples/flower-authentication/README.md

@@ -68,7 +68,9 @@ containing file path to the SuperLink's private key `server_credentials`, and `-
 
 ```bash
 flower-superlink \
-    --certificates certificates/ca.crt certificates/server.pem certificates/server.key \
+    --ssl-ca-certfile certificates/ca.crt \
+    --ssl-certfile certificates/server.pem \
+    --ssl-keyfile certificates/server.key \
     --auth-list-public-keys keys/client_public_keys.csv \
     --auth-superlink-private-key keys/server_credentials \
     --auth-superlink-public-key keys/server_credentials.pub

src/py/flwr/server/app.py

@@ -19,10 +19,10 @@
 import importlib.util
 import sys
 import threading
-from logging import ERROR, INFO, WARN
+from logging import INFO, WARN
 from os.path import isfile
 from pathlib import Path
-from typing import List, Optional, Sequence, Set, Tuple
+from typing import Optional, Sequence, Set, Tuple
 
 import grpc
 from cryptography.exceptions import UnsupportedAlgorithm
@@ -346,6 +346,9 @@ def run_superlink() -> None:
             sys.exit(MISSING_EXTRA_REST)
         address_arg = args.rest_fleet_api_address
         parsed_address = parse_address(address_arg)
+        _, ssl_certfile, ssl_keyfile = (
+            certificates if certificates is not None else (None, None, None)
+        )
         if not parsed_address:
             sys.exit(f"Fleet IP address ({address_arg}) cannot be parsed.")
         host, port, _ = parsed_address
@@ -354,8 +357,8 @@ def run_superlink() -> None:
             args=(
                 host,
                 port,
-                args.ssl_keyfile,
-                args.ssl_certfile,
+                ssl_keyfile,
+                ssl_certfile,
                 state_factory,
                 args.rest_fleet_api_workers,
             ),
@@ -442,8 +445,8 @@ def _try_setup_client_authentication(
     if certificates is None:
         sys.exit(
             "Authentication requires secure connections. "
-            "Please provide certificate paths using '--certificates' and "
-            "try again."
+            "Please provide certificate paths to `--ssl-certfile`, "
+            "`--ssl-keyfile`, and `—-ssl-ca-certfile` and try again."
         )
 
     client_keys_file_path = Path(args.auth_list_public_keys)
@@ -512,21 +515,52 @@ def _try_obtain_certificates(
     # Obtain certificates
     if args.insecure:
         log(WARN, "Option `--insecure` was set. Starting insecure HTTP server.")
-        certificates = None
+        return None
     # Check if certificates are provided
-    elif args.certificates:
-        certificates = (
-            Path(args.certificates[0]).read_bytes(),  # CA certificate
-            Path(args.certificates[1]).read_bytes(),  # server certificate
-            Path(args.certificates[2]).read_bytes(),  # server private key
-        )
-    else:
-        sys.exit(
-            "Certificates are required unless running in insecure mode. "
-            "Please provide certificate paths with '--certificates' or run the server "
-            "in insecure mode using '--insecure' if you understand the risks."
-        )
-    return certificates
+    if args.fleet_api_type == TRANSPORT_TYPE_GRPC_RERE:
+        if args.ssl_certfile and args.ssl_keyfile and args.ssl_ca_certfile:
+            if not isfile(args.ssl_ca_certfile):
+                sys.exit("Path argument `--ssl-ca-certfile` does not point to a file.")
+            if not isfile(args.ssl_certfile):
+                sys.exit("Path argument `--ssl-certfile` does not point to a file.")
+            if not isfile(args.ssl_keyfile):
+                sys.exit("Path argument `--ssl-keyfile` does not point to a file.")
+            certificates = (
+                Path(args.ssl_ca_certfile).read_bytes(),  # CA certificate
+                Path(args.ssl_certfile).read_bytes(),  # server certificate
+                Path(args.ssl_keyfile).read_bytes(),  # server private key
+            )
+            return certificates
+        if args.ssl_certfile or args.ssl_keyfile or args.ssl_ca_certfile:
+            sys.exit(
+                "You need to provide valid file paths to `--ssl-certfile`, "
+                "`--ssl-keyfile`, and `—-ssl-ca-certfile` to create a secure "
+                "connection in Fleet API server (gRPC-rere)."
+            )
+    if args.fleet_api_type == TRANSPORT_TYPE_REST:
+        if args.ssl_certfile and args.ssl_keyfile:
+            if not isfile(args.ssl_certfile):
+                sys.exit("Path argument `--ssl-certfile` does not point to a file.")
+            if not isfile(args.ssl_keyfile):
+                sys.exit("Path argument `--ssl-keyfile` does not point to a file.")
+            certificates = (
+                b"",
+                Path(args.ssl_certfile).read_bytes(),  # server certificate
+                Path(args.ssl_keyfile).read_bytes(),  # server private key
+            )
+            return certificates
+        if args.ssl_certfile or args.ssl_keyfile:
+            sys.exit(
+                "You need to provide valid file paths to `--ssl-certfile` "
+                "and `--ssl-keyfile` to create a secure connection "
+                "in Fleet API server (REST, experimental)."
+            )
+    sys.exit(
+        "Certificates are required unless running in insecure mode. "
+        "Please provide certificate paths to `--ssl-certfile`, "
+        "`--ssl-keyfile`, and `—-ssl-ca-certfile` or run the server "
+        "in insecure mode using '--insecure' if you understand the risks."
+    )
 
 
 def _run_fleet_api_grpc_rere(
@@ -582,14 +616,6 @@ def _run_fleet_api_rest(
     # See: https://www.starlette.io/applications/#accessing-the-app-instance
     fast_api_app.state.STATE_FACTORY = state_factory
 
-    validation_exceptions = _validate_ssl_files(
-        ssl_certfile=ssl_certfile, ssl_keyfile=ssl_keyfile
-    )
-    if any(validation_exceptions):
-        # Starting with 3.11 we can use ExceptionGroup but for now
-        # this seems to be the reasonable approach.
-        raise ValueError(validation_exceptions)
-
     uvicorn.run(
         app="flwr.server.superlink.fleet.rest_rere.rest_api:app",
         port=port,
@@ -602,32 +628,6 @@ def _run_fleet_api_rest(
     )
 
 
-def _validate_ssl_files(
-    ssl_keyfile: Optional[str], ssl_certfile: Optional[str]
-) -> List[ValueError]:
-    validation_exceptions = []
-
-    if ssl_keyfile is not None and not isfile(ssl_keyfile):
-        msg = "Path argument `--ssl-keyfile` does not point to a file."
-        log(ERROR, msg)
-        validation_exceptions.append(ValueError(msg))
-
-    if ssl_certfile is not None and not isfile(ssl_certfile):
-        msg = "Path argument `--ssl-certfile` does not point to a file."
-        log(ERROR, msg)
-        validation_exceptions.append(ValueError(msg))
-
-    if not bool(ssl_keyfile) == bool(ssl_certfile):
-        msg = (
-            "When setting one of `--ssl-keyfile` and "
-            "`--ssl-certfile`, both have to be used."
-        )
-        log(ERROR, msg)
-        validation_exceptions.append(ValueError(msg))
-
-    return validation_exceptions
-
-
 def _parse_args_run_driver_api() -> argparse.ArgumentParser:
     """Parse command line arguments for Driver API."""
     parser = argparse.ArgumentParser(
@@ -684,13 +684,23 @@ def _add_args_common(parser: argparse.ArgumentParser) -> None:
         "Use this flag only if you understand the risks.",
     )
     parser.add_argument(
-        "--certificates",
-        nargs=3,
-        metavar=("CA_CERT", "SERVER_CERT", "PRIVATE_KEY"),
+        "--ssl-certfile",
+        help="Fleet API server SSL certificate file (as a path str) "
+        "to create a secure connection.",
+        type=str,
+        default=None,
+    )
+    parser.add_argument(
+        "--ssl-keyfile",
+        help="Fleet API server SSL private key file (as a path str) "
+        "to create a secure connection.",
+        type=str,
+    )
+    parser.add_argument(
+        "--ssl-ca-certfile",
+        help="Fleet API server SSL CA certificate file (as a path str) "
+        "to create a secure connection.",
         type=str,
-        help="Paths to the CA certificate, server certificate, and server private "
-        "key, in that order. Note: The server can only be started without "
-        "certificates by enabling the `--insecure` flag.",
     )
     parser.add_argument(
         "--database",
@@ -763,18 +773,6 @@ def _add_args_fleet_api(parser: argparse.ArgumentParser) -> None:
         help="Fleet API (REST) server address (IPv4, IPv6, or a domain name)",
         default=ADDRESS_FLEET_API_REST,
     )
-    rest_group.add_argument(
-        "--ssl-certfile",
-        help="Fleet API (REST) server SSL certificate file (as a path str), "
-        "needed for using 'https'.",
-        default=None,
-    )
-    rest_group.add_argument(
-        "--ssl-keyfile",
-        help="Fleet API (REST) server SSL private key file (as a path str), "
-        "needed for using 'https'.",
-        default=None,
-    )
     rest_group.add_argument(
         "--rest-fleet-api-workers",
         help="Set the number of concurrent workers for the Fleet API REST server.",