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# Copyright 2020 The gRPC Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Client of the Python AsyncIO example of customizing authentication mechanism."""
import argparse
import asyncio
import logging
import _credentials
import grpc
helloworld_pb2, helloworld_pb2_grpc = grpc.protos_and_services(
"helloworld.proto")
_LOGGER = logging.getLogger(__name__)
_LOGGER.setLevel(logging.INFO)
_SERVER_ADDR_TEMPLATE = 'localhost:%d'
_SIGNATURE_HEADER_KEY = 'x-signature'
class AuthGateway(grpc.AuthMetadataPlugin):
def __call__(self, context: grpc.AuthMetadataContext,
callback: grpc.AuthMetadataPluginCallback) -> None:
"""Implements authentication by passing metadata to a callback.
Implementations of this method must not block.
Args:
context: An AuthMetadataContext providing information on the RPC that
the plugin is being called to authenticate.
callback: An AuthMetadataPluginCallback to be invoked either
synchronously or asynchronously.
"""
# Example AuthMetadataContext object:
# AuthMetadataContext(
# service_url=u'https://localhost:50051/helloworld.Greeter',
# method_name=u'SayHello')
signature = context.method_name[::-1]
callback(((_SIGNATURE_HEADER_KEY, signature),), None)
def create_client_channel(addr: str) -> grpc.aio.Channel:
# Call credential object will be invoked for every single RPC
call_credentials = grpc.metadata_call_credentials(AuthGateway(),
name='auth gateway')
# Channel credential will be valid for the entire channel
channel_credential = grpc.ssl_channel_credentials(
_credentials.ROOT_CERTIFICATE)
# Combining channel credentials and call credentials together
composite_credentials = grpc.composite_channel_credentials(
channel_credential,
call_credentials,
)
channel = grpc.aio.secure_channel(addr, composite_credentials)
return channel
async def send_rpc(channel: grpc.aio.Channel) -> helloworld_pb2.HelloReply:
stub = helloworld_pb2_grpc.GreeterStub(channel)
request = helloworld_pb2.HelloRequest(name='you')
try:
response = await stub.SayHello(request)
except grpc.RpcError as rpc_error:
_LOGGER.error('Received error: %s', rpc_error)
return rpc_error
else:
_LOGGER.info('Received message: %s', response)
return response
async def main() -> None:
parser = argparse.ArgumentParser()
parser.add_argument('--port',
nargs='?',
type=int,
default=50051,
help='the address of server')
args = parser.parse_args()
channel = create_client_channel(_SERVER_ADDR_TEMPLATE % args.port)
await send_rpc(channel)
await channel.close()
if __name__ == '__main__':
logging.basicConfig(level=logging.INFO)
asyncio.run(main())
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