What version of gRPC and what language are you using?

1.17.1

What operating system (Linux, Windows, …) and version?

Linux (Debian Buster)

What runtime / compiler are you using (e.g. python version or version of gcc)

Python 3.7.2

What did you do?

I am trying to write Grpc client in python for a Grpc server written in go. My client code looks like

with open('server.crt', 'rb') as f:    trusted_certs = f.read()

credentials = grpc.ssl_channel_credentials(trusted_certs)
ops = [('grpc.ssl_target_name_override', 'secure.app')]
channel = grpc.secure_channel('localhost:443', credentials, ops)
stub =  SomeStub(channel)
stub.SomeMethod(Request())

but for some reasons it's unable to connect to the server, giving me CERTIFICATE_VERIFY_FAILED error.

What did you expect to see?

I expected client to connect to the server, because my go client works perfectly well but python client isn't working well. Here's my what my go client looks like

       var opts []grpc.DialOption

	caFile := testdata.Path(crtPath)


	creds, _ := credentials.NewClientTLSFromFile(caFile, "secure.app")

	opts = append(opts, grpc.WithTransportCredentials(creds))
	conn, _ := grpc.Dial("localhost:443", opts...)
        defer conn.Close()
	client := grpc_api.SomeClient(conn)
	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)

	res, _ := client.SomeMethod(ctx, &grpc_api.Request{})

What did you see instead?

Instead I saw following error

E0110 19:17:10.922064705   23315 ssl_transport_security.cc:1229] Handshake failed with fatal error SSL_ERROR_SSL: error:1000007d:SSL routines:OPENSSL_internal:CERTIFICATE_VERIFY_FAILED.