How to communicate the GRPC server with Python client

[dwang-git]

I'm trying to create a client with Python to communicate with the example GreeterService. Here is how I set up the client with Python:

1. Use the command to export ASP.Net development certificate as suggested in this link:
   dotnet dev-certs https --export-path aspnet_cert.cert
2. Generate the greet_pb2_grpc.py and greet_pb2.py using the command:
   python -m grpc_tools.protoc -I=. --python_out=. --pyi_out=. --grpc_python_out=. greet.proto
3. Create the greeter_client.py as below:

    import grpc
    import greet_pb2
    import greet_pb2_grpc
    from os import environ
    environ["GRPC_DNS_RESOLVER"] = "native"
   
    def run_command():
       with open('aspnet_cert.cert', 'rb') as f:
           credentials = grpc.ssl_channel_credentials(f.read())
           # channel = grpc.secure_channel('dns:localhost:5001', credentials)
           # channel = grpc.secure_channel('localhost:5001', credentials)
           # channel = grpc.secure_channel('{ip}:50051', credentials)
           channel = grpc.secure_channel('https://localhost:5001', credentials)
           stub = greet_pb2_grpc.GreeterStub(channel)
           request = greet_pb2.HelloRequest(name = "Python_GreeterClient" )
           response = stub.SayHello(request)
           print(response.message)
   
   if __name__ == '__main__':
       run_command()
   

But when I run greeter_client.py, I would always get the error below. 


> <_InactiveRpcError of RPC that terminated with:
> 	status = StatusCode.UNAVAILABLE
> 	details = "DNS resolution failed for https://localhost:5001: UNAVAILABLE: getaddrinfo: WSA Error (No such host is known.
>  -- 11001)"
> 	debug_error_string = "UNKNOWN:Error received from peer  {grpc_message:"DNS resolution failed for https://localhost:5001: UNAVAILABLE: getaddrinfo: WSA Error (No such host is known.\r\n -- 11001)", grpc_status:14, created_time:"2024-12-09T19:52:27.9184037+00:00"}"
> >
>   File "C:\Cortina\Python_cableeye_wrapper\greeter_client.py", line 16, in run_command
>     response = stub.SayHello(request)
>   File "C:\Cortina\Python_cableeye_wrapper\greeter_client.py", line 20, in <module>
>     run_command()

and in the console output, I see this:

> E0000 00:00:1733783545.954314   13220 ssl_transport_security.cc:755] Could not load any root certificate.     
> E0000 00:00:1733783545.956913   13220 ssl_transport_security.cc:2302] Cannot load server root certificates.   
> E0000 00:00:1733783545.957548   13220 ssl_credentials.cc:215] Handshaker factory creation failed with TSI_INVALID_ARGUMENT

Seems the certificate was not generated correctly?

I tried some other ways of creating the channel, but none of them works so far.
Thanks!

[JamesNK]

Please ask questions about configuring a python client in the python gRPC repository. I don't know how it works.

[dwang-git]

Can you point out the link of the python gRPC repository? Thanks!