xref: /aosp_15_r20/external/grpc-grpc/examples/python/auth/async_customized_auth_client.py (revision cc02d7e222339f7a4f6ba5f422e6413f4bd931f2) 
1# Copyright 2020 The gRPC Authors
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14"""Client of the Python AsyncIO example of customizing authentication mechanism."""
15
16import argparse
17import asyncio
18import logging
19
20import _credentials
21import grpc
22
23helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
24    "helloworld.proto"
25)
26
27_LOGGER = logging.getLogger(__name__)
28_LOGGER.setLevel(logging.INFO)
29
30_SERVER_ADDR_TEMPLATE = "localhost:%d"
31_SIGNATURE_HEADER_KEY = "x-signature"
32
33
34class AuthGateway(grpc.AuthMetadataPlugin):
35    def __call__(
36        self,
37        context: grpc.AuthMetadataContext,
38        callback: grpc.AuthMetadataPluginCallback,
39    ) -> None:
40        """Implements authentication by passing metadata to a callback.
41
42        Implementations of this method must not block.
43
44        Args:
45          context: An AuthMetadataContext providing information on the RPC that
46            the plugin is being called to authenticate.
47          callback: An AuthMetadataPluginCallback to be invoked either
48            synchronously or asynchronously.
49        """
50        # Example AuthMetadataContext object:
51        # AuthMetadataContext(
52        #     service_url=u'https://localhost:50051/helloworld.Greeter',
53        #     method_name=u'SayHello')
54        signature = context.method_name[::-1]
55        callback(((_SIGNATURE_HEADER_KEY, signature),), None)
56
57
58def create_client_channel(addr: str) -> grpc.aio.Channel:
59    # Call credential object will be invoked for every single RPC
60    call_credentials = grpc.metadata_call_credentials(
61        AuthGateway(), name="auth gateway"
62    )
63    # Channel credential will be valid for the entire channel
64    channel_credential = grpc.ssl_channel_credentials(
65        _credentials.ROOT_CERTIFICATE
66    )
67    # Combining channel credentials and call credentials together
68    composite_credentials = grpc.composite_channel_credentials(
69        channel_credential,
70        call_credentials,
71    )
72    channel = grpc.aio.secure_channel(addr, composite_credentials)
73    return channel
74
75
76async def send_rpc(channel: grpc.aio.Channel) -> helloworld_pb2.HelloReply:
77    stub = helloworld_pb2_grpc.GreeterStub(channel)
78    request = helloworld_pb2.HelloRequest(name="you")
79    try:
80        response = await stub.SayHello(request)
81    except grpc.RpcError as rpc_error:
82        _LOGGER.error("Received error: %s", rpc_error)
83        return rpc_error
84    else:
85        _LOGGER.info("Received message: %s", response)
86        return response
87
88
89async def main() -> None:
90    parser = argparse.ArgumentParser()
91    parser.add_argument(
92        "--port",
93        nargs="?",
94        type=int,
95        default=50051,
96        help="the address of server",
97    )
98    args = parser.parse_args()
99
100    channel = create_client_channel(_SERVER_ADDR_TEMPLATE % args.port)
101    await send_rpc(channel)
102    await channel.close()
103
104
105if __name__ == "__main__":
106    logging.basicConfig(level=logging.INFO)
107    asyncio.run(main())
108