Grpc server started but cannot connect

[jeffreychuuu]

I'm using kotlin with spring boot building by gradle. The log shows that grpc server was listening on port 9090, while when I use BloobRpc to test if the server works, it reflects "error": "12 UNIMPLEMENTED: Method not found: demo.Greeter/SayHello".

My GrpcServerService basically is written by Java as below

@GrpcService
public class GrpcServerService extends GreeterGrpc.GreeterImplBase {
    @Override
    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
        HelloReply reply = HelloReply.newBuilder().setMessage("Hello ==> " + req.getName()).build();
        responseObserver.onNext(reply);
        responseObserver.onCompleted();
    }
}

Does anyone knows how to resolve this issue?

[ST-DDT]

As you can see in the logs, the server did not find/register the grpc service.
Can you please check that the bean is actually created.

[jeffreychuuu]

The grpc server should have started correctly since once I changed the port to others in BloomRpc the error code is not "error": "12 UNIMPLEMENTED: Method not found: demo.Greeter/SayHello". It was "error": "14 UNAVAILABLE: failed to connect to all addresses" instead.

[jeffreychuuu]

Would be appreciated that if you don't mind help me to check through my app. It locates at https://github.com/jeffreychu-org/kotlin_example_app in grpc-issue branch.

It may tested simply be

1. cd /rdbms_service
2. docker-compose up -d to start the PostgreSQL and redis
3. simple start the spring boot app and it will trigger the other project grpc_lib to generate the grpc stub for use

This issue struggle me a few days. Many thanks. Cheers.

[ST-DDT]

$ docker compose up
(root) Additional property postgres is not allowed

I have trouble starting the docker compose on my computer (I haven't used it here before).
Maybe Windows doesn't like docker compose?

I still managed to start the application by stripping it of the other components.
FFR: Please reference only minimal workign examples not a project that showcases all.

2021-09-29 21:38:40.805  INFO 2888 --- [           main] n.d.b.g.s.s.AbstractGrpcServerFactory    : Registered gRPC service: grpc.health.v1.Health, bean: grpcHealthService, class: io.grpc.services.HealthServiceImpl
2021-09-29 21:38:40.805  INFO 2888 --- [           main] n.d.b.g.s.s.AbstractGrpcServerFactory    : Registered gRPC service: grpc.reflection.v1alpha.ServerReflection, bean: protoReflectionService, class: io.grpc.protobuf.services.ProtoReflectionService
2021-09-29 21:38:41.220  INFO 2888 --- [           main] n.d.b.g.s.s.GrpcServerLifecycle          : gRPC Server started, listening on address: *, port: 9090
2021-09-29 21:38:41.230  INFO 2888 --- [           main] c.e.k.KotlinExampleAppApplicationKt      : Started KotlinExampleAppApplicationKt in 3.566 seconds (JVM running for 4.106)

As you can see the server detected the two default grpc services ( ServerReflection, Health ).
But it didn't detect your GrpcServerService, nor did it execute its afterPropertiesSet method.
So the issue here is that the service doesn't get recognized as bean.
I tried to annotate it with @Component but doesn't seem to do the trick either.

I checked the jar and the class wasn't present there, so I suspect there is an issue with your build gradle that ignores plain java files.

[jeffreychuuu]

Yes. That's what I'm also suspecting that if we can have hybird spring boot application with boot kotlin and java since I found that the bean is not created. Anyway, does this starter package support kotlin version? Since I know the message files generated by protoc are still java. Or is there any example of integrating with kotlin about this starter so I can get a try.

I'm wondering if this issue related.

[ST-DDT]

Kotlin is definitely supported by this project.
https://github.com/yidongnan/grpc-spring-boot-starter/blob/master/docs/en/flavors.md
At this point you only have to add java support to your kotlin project.
Please refer to the official gradle/kotlin documentation or StackOverflow on how to do that.
Maybe all you have to do is adding the java library plugin.

[ST-DDT]

See also https://github.com/yidongnan/grpc-spring-boot-starter/pull/412