How to deploy gRPC server/client to heroku?

Question

I deployed my python gRPC server to Heroku and was wondering how I could test it with a local Python client.

server.py

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    icp_pb2_grpc.add_MyServicer_to_server(MyServicer(), server)

    server_port = os.environ.get('PORT', 50051) 
    server.add_insecure_port('[::]:'+ str(server_port))
    server.start()
    print("==== SERVER RUNNING =====")
    try:
        while True:
            time.sleep(_ONE_DAY_IN_SECONDS)
    except KeyboardInterrupt:
        server.stop(0)

if __name__ == '__main__':
    serve()

client.py

def run():
    # Is the channel url correct?
    channel = grpc.insecure_channel('https://www.HEROKUURL.com:50051')
    stub = my_grpc.MyStub(channel)
    file = _get_file_content()
    response = stub.Predict(icp_pb2.MyRequest(file_content=file))
    print("received: " + response.results)

I am using the client from my computer and am not receiving any response from the server. I am able to successfully communicate with the server if it is launched locally. What am I doing wrong?

Answer 1

Heroku does not support HTTP 2. On the other hand, GRPC uses a http/2 based transport. I think that's why you can connect it locally but not from Heroku.