How do I pass bearer token and other info from Spring Service to Grpc Interceptor?-CodePudding

I have a Spring GraphQL application that calls the other internal microservice using the gRPC protocol. I need to set the bearer token and other information to the gRPC header, I believe we can set it up using the gRPC interceptor (ClientInterceptor implementation).

I tried the below approach:

Based on How to Access attributes from grpc Context.current()? I created a key so that we can refer it in spring-service and interceptor

public class ContextKeyHolder {
  public static Context.Key<String> USER_INFO = Context.key("USER");
  public static Context.Key<String> BEARER = Context.key("BEARER");
}

// spring-service method
public Employee getEmployee() {
  ...
  Context.current().withValue(ContextKeyHolder.USER_INFO, currentUser.getUsername());
  Context.current().withValue(ContextKeyHolder.BEARER, currentUser.getBearerToken());
  return grpcClient.getEmployee(...);
}

// interceptCall implementation
public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> methodDescriptor,
    CallOptions callOptions, Channel channel) {
    return new ForwardingClientCall.SimpleForwardingClientCall<>(
      channel.newCall(methodDescriptor, callOptions)) {
     
      @Override
      public void start(Listener<RespT> responseListener, Metadata headers) {
        ...
        
        String userInfo = ContextKeyHolder.USER_INFO.get(Context.current());
        System.out.println("user => "   userInfo);
        
        ...
        super.start(responseListener, headers);
      }
    };
  }

Here I am getting null userInfo in the interceptor method. am I missing something here?

The other option is to use ThreadLocal to hold the context but I am kind of not sure if it's the right choice here.

CodePudding user response：

The context you created needs to be used when you make the call. So your code should be:

return Context.current()
   .withValue(ContextKeyHolder.USER_INFO, currentUser.getUsername())
   .withValue(ContextKeyHolder.BEARER, currentUser.getBearerToken())
   .call(() -> { return grpcClient.getEmployee(...);});

Alternatively:

  Context oldContext = 
   Context.current()
     .withValue(ContextKeyHolder.USER_INFO, currentUser.getUsername())
     .withValue(ContextKeyHolder.BEARER, currentUser.getBearerToken())
     .attach();
  
  Employee valueToReturn = grpcClient.getEmployee(...);
  Context.current().detach(oldContext);
  return valueToReturn;