getAttributes() always empty if called from SimpleForwardingClientCall

What version of gRPC are you using?

1.10.0

What did you expect to see?

Let’s say we have the following client interceptor which is attached to our channel:

class LoggingClientInterceptor implements ClientInterceptor {

  private static final Logger log = LoggerFactory.getLogger(LoggingClientInterceptor.class);

  @Override
  public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method,
      CallOptions callOptions, Channel next) {
    return new SimpleForwardingClientCall<ReqT, RespT>(next.newCall(method, callOptions)) {
      @Override
      public void start(Listener<RespT> responseListener, Metadata headers) {
        log.info("grpc request; method: {}, attributes: {}", method.getFullMethodName(),
            getAttributes());

        super.start(responseListener, headers);
      }
    };
  }
}

When calling the getAttributes() method I expected to see a set of attributes which contains at least the information about the server to which the client is going to make a request to. Unfortunately, getAttributes() method always empty.

[dapengzhang0]

+1

Do you happen to be using plaintext?

@maseev, your updated interceptor will work correctly. But if you are using plaintext, no attributes will be added by the grpc library. If you are using Netty transport with TLS, two attributes may be added: Grpc.TRANSPORT_ATTR_SSL_SESSION and Grpc.TRANSPORT_ATTR_REMOTE_ADDR

[maseev]

Oh, I didn’t know that. I do use plaintext actually. I guess that explains everything. Thank you for your help @zpencer @dapengzhang0.