examples/python/metadata/metadata_server.py

# Copyright 2018 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.
"""Example gRPC server that gets/sets metadata (HTTP2 headers)"""

from __future__ import print_function

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):
        for key, value in context.invocation_metadata():
            print("Received initial metadata: key=%s value=%s" % (key, value))

        context.set_trailing_metadata(
            (
                ("checksum-bin", b"I agree"),
                ("retry", "false"),
            )
        )
        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()