[fed] Fixes for the encrypted GRPC backend.

plugin/federated/federated_comm.cc

@@ -1,5 +1,5 @@
 /**
- * Copyright 2023, XGBoost contributors
+ * Copyright 2023-2024, XGBoost contributors
  */
 #include "federated_comm.h"
 
@@ -11,6 +11,7 @@
 #include <string>   // for string, stoi
 
 #include "../../src/common/common.h"      // for Split
+#include "../../src/common/io.h"          // for ReadAll
 #include "../../src/common/json_utils.h"  // for OptionalArg
 #include "xgboost/json.h"                 // for Json
 #include "xgboost/logging.h"
@@ -46,9 +47,9 @@ void FederatedComm::Init(std::string const& host, std::int32_t port, std::int32_
   } else {
     stub_ = [&] {
       grpc::SslCredentialsOptions options;
-      options.pem_root_certs = server_cert;
-      options.pem_private_key = client_key;
-      options.pem_cert_chain = client_cert;
+      options.pem_root_certs = common::ReadAll(server_cert);
+      options.pem_private_key = common::ReadAll(client_key);
+      options.pem_cert_chain = common::ReadAll(client_cert);
       grpc::ChannelArguments args;
       args.SetMaxReceiveMessageSize(std::numeric_limits<std::int32_t>::max());
       auto channel = grpc::CreateCustomChannel(host + ":" + std::to_string(port),

python-package/xgboost/federated.py

@@ -39,9 +39,9 @@ def __init__(  # pylint: disable=R0913, W0231
         n_workers: int,
         port: int,
         secure: bool,
-        server_key_path: str = "",
-        server_cert_path: str = "",
-        client_cert_path: str = "",
+        server_key_path: Optional[str] = None,
+        server_cert_path: Optional[str] = None,
+        client_cert_path: Optional[str] = None,
         timeout: int = 300,
     ) -> None:
         handle = ctypes.c_void_p()
@@ -84,7 +84,13 @@ def run_federated_server(  # pylint: disable=too-many-arguments
         for path in [server_key_path, server_cert_path, client_cert_path]
     )
     tracker = FederatedTracker(
-        n_workers=n_workers, port=port, secure=secure, timeout=timeout
+        n_workers=n_workers,
+        port=port,
+        secure=secure,
+        timeout=timeout,
+        server_key_path=server_key_path,
+        server_cert_path=server_cert_path,
+        client_cert_path=client_cert_path,
     )
     tracker.start()
 

python-package/xgboost/testing/federated.py

@@ -0,0 +1,153 @@
+# pylint: disable=unbalanced-tuple-unpacking, too-many-locals
+"""Tests for federated learning."""
+
+import multiprocessing
+import os
+import subprocess
+import tempfile
+import time
+from typing import List, cast
+
+from sklearn.datasets import dump_svmlight_file, load_svmlight_file
+from sklearn.model_selection import train_test_split
+
+import xgboost as xgb
+import xgboost.federated
+from xgboost import testing as tm
+from xgboost.training import TrainingCallback
+
+SERVER_KEY = "server-key.pem"
+SERVER_CERT = "server-cert.pem"
+CLIENT_KEY = "client-key.pem"
+CLIENT_CERT = "client-cert.pem"
+
+
+def run_server(port: int, world_size: int, with_ssl: bool) -> None:
+    """Run federated server for test."""
+    if with_ssl:
+        xgboost.federated.run_federated_server(
+            world_size,
+            port,
+            server_key_path=SERVER_KEY,
+            server_cert_path=SERVER_CERT,
+            client_cert_path=CLIENT_CERT,
+        )
+    else:
+        xgboost.federated.run_federated_server(world_size, port)
+
+
+def run_worker(
+    port: int, world_size: int, rank: int, with_ssl: bool, device: str
+) -> None:
+    """Run federated client worker for test."""
+    communicator_env = {
+        "dmlc_communicator": "federated",
+        "federated_server_address": f"localhost:{port}",
+        "federated_world_size": world_size,
+        "federated_rank": rank,
+    }
+    if with_ssl:
+        communicator_env["federated_server_cert_path"] = SERVER_CERT
+        communicator_env["federated_client_key_path"] = CLIENT_KEY
+        communicator_env["federated_client_cert_path"] = CLIENT_CERT
+
+    cpu_count = os.cpu_count()
+    assert cpu_count is not None
+    n_threads = cpu_count // world_size
+
+    # Always call this before using distributed module
+    with xgb.collective.CommunicatorContext(**communicator_env):
+        # Load file, file will not be sharded in federated mode.
+        X, y = load_svmlight_file(f"agaricus.txt-{rank}.train")
+        dtrain = xgb.DMatrix(X, y)
+        X, y = load_svmlight_file(f"agaricus.txt-{rank}.test")
+        dtest = xgb.DMatrix(X, y)
+
+        # Specify parameters via map, definition are same as c++ version
+        param = {
+            "max_depth": 2,
+            "eta": 1,
+            "objective": "binary:logistic",
+            "nthread": n_threads,
+            "tree_method": "hist",
+            "device": device,
+        }
+
+        # Specify validations set to watch performance
+        watchlist = [(dtest, "eval"), (dtrain, "train")]
+        num_round = 20
+
+        # Run training, all the features in training API is available.
+        results: TrainingCallback.EvalsLog = {}
+        bst = xgb.train(
+            param,
+            dtrain,
+            num_round,
+            evals=watchlist,
+            early_stopping_rounds=2,
+            evals_result=results,
+        )
+        assert tm.non_increasing(cast(List[float], results["train"]["logloss"]))
+        assert tm.non_increasing(cast(List[float], results["eval"]["logloss"]))
+
+        # save the model, only ask process 0 to save the model.
+        if xgb.collective.get_rank() == 0:
+            with tempfile.TemporaryDirectory() as tmpdir:
+                bst.save_model(os.path.join(tmpdir, "model.json"))
+            xgb.collective.communicator_print("Finished training\n")
+
+
+def run_federated(world_size: int, with_ssl: bool, use_gpu: bool) -> None:
+    """Launcher for clients and the server."""
+    port = 9091
+
+    server = multiprocessing.Process(
+        target=run_server, args=(port, world_size, with_ssl)
+    )
+    server.start()
+    time.sleep(1)
+    if not server.is_alive():
+        raise ValueError("Error starting Federated Learning server")
+
+    workers = []
+    for rank in range(world_size):
+        device = f"cuda:{rank}" if use_gpu else "cpu"
+        worker = multiprocessing.Process(
+            target=run_worker, args=(port, world_size, rank, with_ssl, device)
+        )
+        workers.append(worker)
+        worker.start()
+    for worker in workers:
+        worker.join()
+    server.terminate()
+
+
+def run_federated_learning(with_ssl: bool, use_gpu: bool, test_path: str) -> None:
+    """Run federated learning tests."""
+    n_workers = 2
+
+    if with_ssl:
+        command = "openssl req -x509 -newkey rsa:2048 -days 7 -nodes -keyout {part}-key.pem -out {part}-cert.pem -subj /C=US/CN=localhost"  # pylint: disable=line-too-long
+        server_key = command.format(part="server").split()
+        subprocess.check_call(server_key)
+        client_key = command.format(part="client").split()
+        subprocess.check_call(client_key)
+
+    train_path = os.path.join(tm.data_dir(test_path), "agaricus.txt.train")
+    test_path = os.path.join(tm.data_dir(test_path), "agaricus.txt.test")
+
+    X_train, y_train = load_svmlight_file(train_path)
+    X_test, y_test = load_svmlight_file(test_path)
+
+    X0, X1, y0, y1 = train_test_split(X_train, y_train, test_size=0.5)
+    X0_valid, X1_valid, y0_valid, y1_valid = train_test_split(
+        X_test, y_test, test_size=0.5
+    )
+
+    dump_svmlight_file(X0, y0, "agaricus.txt-0.train")
+    dump_svmlight_file(X0_valid, y0_valid, "agaricus.txt-0.test")
+
+    dump_svmlight_file(X1, y1, "agaricus.txt-1.train")
+    dump_svmlight_file(X1_valid, y1_valid, "agaricus.txt-1.test")
+
+    run_federated(world_size=n_workers, with_ssl=with_ssl, use_gpu=use_gpu)

src/context.cc

@@ -191,8 +191,11 @@ DeviceOrd CUDAOrdinal(DeviceOrd device, bool) {
   }
   if (device.IsCUDA()) {
     device = CUDAOrdinal(device, fail_on_invalid_gpu_id);
+    if (!device.IsCUDA()) {
+      // We allow loading a GPU-based pickle on a CPU-only machine.
+      LOG(WARNING) << "XGBoost is not compiled with CUDA support.";
+    }
   }
-
   return device;
 }
 }  // namespace

tests/ci_build/lint_python.py

@@ -34,6 +34,8 @@ class LintersPaths:
         "tests/python/test_with_pandas.py",
         "tests/python-gpu/",
         "tests/python-sycl/",
+        "tests/test_distributed/test_federated/",
+        "tests/test_distributed/test_gpu_federated/",
         "tests/test_distributed/test_with_dask/",
         "tests/test_distributed/test_gpu_with_dask/",
         "tests/test_distributed/test_with_spark/",
@@ -94,6 +96,8 @@ class LintersPaths:
         "tests/python-gpu/load_pickle.py",
         "tests/python-gpu/test_gpu_training_continuation.py",
         "tests/python/test_model_io.py",
+        "tests/test_distributed/test_federated/",
+        "tests/test_distributed/test_gpu_federated/",
         "tests/test_distributed/test_with_spark/test_data.py",
         "tests/test_distributed/test_gpu_with_spark/test_data.py",
         "tests/test_distributed/test_gpu_with_dask/test_gpu_with_dask.py",

tests/ci_build/test_python.sh

@@ -70,6 +70,7 @@ case "$suite" in
     pytest -v -s -rxXs --fulltrace --durations=0 -m "mgpu" ${args} tests/python-gpu
     pytest -v -s -rxXs --fulltrace --durations=0 -m "mgpu" ${args} tests/test_distributed/test_gpu_with_dask
     pytest -v -s -rxXs --fulltrace --durations=0 -m "mgpu" ${args} tests/test_distributed/test_gpu_with_spark
+    pytest -v -s -rxXs --fulltrace --durations=0 -m "mgpu" ${args} tests/test_distributed/test_gpu_federated
     unset_pyspark_envs
     uninstall_xgboost
     set +x
@@ -84,6 +85,7 @@ case "$suite" in
     pytest -v -s -rxXs --fulltrace --durations=0 ${args} tests/python
     pytest -v -s -rxXs --fulltrace --durations=0 ${args} tests/test_distributed/test_with_dask
     pytest -v -s -rxXs --fulltrace --durations=0 ${args} tests/test_distributed/test_with_spark
+    pytest -v -s -rxXs --fulltrace --durations=0 ${args} tests/test_distributed/test_federated
     unset_pyspark_envs
     uninstall_xgboost
     set +x

tests/test_distributed/test_federated/test_federated.py

@@ -1,86 +1,8 @@
-#!/usr/bin/python
-import multiprocessing
-import sys
-import time
+import pytest
 
-import xgboost as xgb
-import xgboost.federated
+from xgboost.testing.federated import run_federated_learning
 
-SERVER_KEY = 'server-key.pem'
-SERVER_CERT = 'server-cert.pem'
-CLIENT_KEY = 'client-key.pem'
-CLIENT_CERT = 'client-cert.pem'
 
-
-def run_server(port: int, world_size: int, with_ssl: bool) -> None:
-    if with_ssl:
-        xgboost.federated.run_federated_server(port, world_size, SERVER_KEY, SERVER_CERT,
-                                               CLIENT_CERT)
-    else:
-        xgboost.federated.run_federated_server(port, world_size)
-
-
-def run_worker(port: int, world_size: int, rank: int, with_ssl: bool, with_gpu: bool) -> None:
-    communicator_env = {
-        'xgboost_communicator': 'federated',
-        'federated_server_address': f'localhost:{port}',
-        'federated_world_size': world_size,
-        'federated_rank': rank
-    }
-    if with_ssl:
-        communicator_env['federated_server_cert'] = SERVER_CERT
-        communicator_env['federated_client_key'] = CLIENT_KEY
-        communicator_env['federated_client_cert'] = CLIENT_CERT
-
-    # Always call this before using distributed module
-    with xgb.collective.CommunicatorContext(**communicator_env):
-        # Load file, file will not be sharded in federated mode.
-        dtrain = xgb.DMatrix('agaricus.txt.train-%02d?format=libsvm' % rank)
-        dtest = xgb.DMatrix('agaricus.txt.test-%02d?format=libsvm' % rank)
-
-        # Specify parameters via map, definition are same as c++ version
-        param = {'max_depth': 2, 'eta': 1, 'objective': 'binary:logistic'}
-        if with_gpu:
-            param['tree_method'] = 'hist'
-            param['device'] = f"cuda:{rank}"
-
-        # Specify validations set to watch performance
-        watchlist = [(dtest, 'eval'), (dtrain, 'train')]
-        num_round = 20
-
-        # Run training, all the features in training API is available.
-        bst = xgb.train(param, dtrain, num_round, evals=watchlist,
-                        early_stopping_rounds=2)
-
-        # Save the model, only ask process 0 to save the model.
-        if xgb.collective.get_rank() == 0:
-            bst.save_model("test.model.json")
-            xgb.collective.communicator_print("Finished training\n")
-
-
-def run_federated(with_ssl: bool = True, with_gpu: bool = False) -> None:
-    port = 9091
-    world_size = int(sys.argv[1])
-
-    server = multiprocessing.Process(target=run_server, args=(port, world_size, with_ssl))
-    server.start()
-    time.sleep(1)
-    if not server.is_alive():
-        raise Exception("Error starting Federated Learning server")
-
-    workers = []
-    for rank in range(world_size):
-        worker = multiprocessing.Process(target=run_worker,
-                                         args=(port, world_size, rank, with_ssl, with_gpu))
-        workers.append(worker)
-        worker.start()
-    for worker in workers:
-        worker.join()
-    server.terminate()
-
-
-if __name__ == '__main__':
-    run_federated(with_ssl=True, with_gpu=False)
-    run_federated(with_ssl=False, with_gpu=False)
-    run_federated(with_ssl=True, with_gpu=True)
-    run_federated(with_ssl=False, with_gpu=True)
+@pytest.mark.parametrize("with_ssl", [True, False])
+def test_federated_learning(with_ssl: bool) -> None:
+    run_federated_learning(with_ssl, False, __file__)

tests/test_distributed/test_gpu_federated/test_gpu_federated.py

@@ -0,0 +1,9 @@
+import pytest
+
+from xgboost.testing.federated import run_federated_learning
+
+
+@pytest.mark.parametrize("with_ssl", [True, False])
+@pytest.mark.mgpu
+def test_federated_learning(with_ssl: bool) -> None:
+    run_federated_learning(with_ssl, True, __file__)