Pythonを使ったgRPCにおけるエラーについて

Question

質問した経緯

gRPCの公式ドキュメントに載っているPythonのプログラムについてエラーが発生しました。
いろいろ調べたのですが解決策がわからず、ご教授お願い致します。

前提条件（環境）

• Windows10
• VisualStudioCode
• Python3.8.8
• Anaconda(仮想環境)

エラーが発生する流れ

gRPCの公式ドキュメントの流れに沿って実施

1. grpcioのインストール
2. gRPCツールのインストール
3. サンプルプログラムをGitからダウンロード
4. VisualStudioCodeのターミナルからgRPCアプリケーション(サーバー)を実行
   python greeter_server.py
5. VisualStudioCodeから別のターミナルを立ち上げてgRPCアプリケーション(クライアント)を実行
   python greeter_client.py

5.の実行結果として、下記のエラーとなってしまいます。

(py38) PS C:\Users\testuser.conda\virtualenv\grpc\examples\python\helloworld>python .\greeter_client.py
Traceback (most recent call last):
  File ".\greeter_client.py", line 38, in <module>
    run()
  File ".\greeter_client.py", line 32, in run
    response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))
  File "C:\Users\testuser\Anaconda3\envs\py38\lib\site-packages\grpc\_channel.py", line 923, in __call__
    return _end_unary_response_blocking(state, call, False, None)
  File "C:\Users\testuser\Anaconda3\envs\py38\lib\site-packages\grpc\_channel.py", line 826, in _end_unary_response_blocking
    raise _InactiveRpcError(state)
grpc._channel._InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
        status = StatusCode.UNAVAILABLE
        details = "failed to connect to all addresses"
        debug_error_string = "{"created":"@1617865971.134000000","description":"Failed to pick subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc"t_channel.cc","file_line":5391,"referenced_errors":[{"created":"@1617865971.134000000","description":"failed to connect to all addresses","file":"src/core/eient_channel/,"file_line":5391,"referenced_errors":[{"created":"@1617865971.134000000","description":"failxt/filters/client_channel/lb_policy/pick_first/pick_first.cc","file_line":398,"grpc_status":14}]}"

調べたこと

• failed to connect to all addressesと出ているため、pythonコードで開けたポート（自身の端末）に対して、疎通確認

Test-NetConnection localhost -Port 50051

• 結果

ComputerName     : localhost
RemoteAddress    : ::1
RemotePort       : 50051
InterfaceAlias   : Loopback Pseudo-Interface 1
SourceAddress    : ::1
TcpTestSucceeded : True

TcpTestSucceeded の結果がTrueになっているため、通信はできると思ってます。

ソースコード

• Gitからダウンロードしたコードそのまま
• greeter_server.py

# Copyright 2015 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.
"""The Python implementation of the GRPC helloworld.Greeter server."""

from concurrent import futures
import logging

import grpc

import helloworld_pb2
import helloworld_pb2_grpc


class Greeter(helloworld_pb2_grpc.GreeterServicer):

    def SayHello(self, request, context):
        return helloworld_pb2.HelloReply(message='Hello, %s!' % request.name)


def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    server.wait_for_termination()


if __name__ == '__main__':
    logging.basicConfig()
    serve()

• greeter_client.py

# Copyright 2015 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.
"""The Python implementation of the GRPC helloworld.Greeter client."""

from __future__ import print_function
import logging

import grpc


import helloworld_pb2
import helloworld_pb2_grpc


def run():
    # NOTE(gRPC Python Team): .close() is possible on a channel and should be
    # used in circumstances in which the with statement does not fit the needs
    # of the code.
    with grpc.insecure_channel('localhost:50051') as channel:
        stub = helloworld_pb2_grpc.GreeterStub(channel)
        response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))
    print("Greeter client received: " + response.message)


if __name__ == '__main__':
    logging.basicConfig()
    run()