Connection refused: localhost/0:0:0:0:0:0:0:1:9000 with gRPC

Question

I creating a gRPC server but everything seems to run okay but the server never starts up on the specifies port and application is throwing no errors. But when I test with telnet on that specific port, I get this from terminal

isaack$ telnet localhost 9000
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
telnet: Unable to connect to remote host

Below is my code to create the server (NB: All the services are generated okay with proto and the generated code has no errors)

import java.io.File;

import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.ServerInterceptors;
import io.grpc.ServerServiceDefinition;

public class EmployeeServiceServer {

    private Server server;

    public static void main(String[] args) {
        try {
            EmployeeServiceServer service = new EmployeeServiceServer();
            service.start();
        } catch (Exception e) {
            System.err.println(e);
        }
    }

    private void start() throws InterruptedException {
        File certificate = new File("/Users/i/certificates/cert.pem");
        File key = new File("/Users/i/certificates/key.pem");
        final int port = 9000;
        EmployeeService employeeService = new EmployeeService();
        ServerServiceDefinition serverServiceDefinition = ServerInterceptors.interceptForward(employeeService,
                new HeaderServerInterceptor());
        server = ServerBuilder.forPort(port).useTransportSecurity(certificate, key).addService(serverServiceDefinition)
                .build();

        System.out.println("Listening on Port " + port);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                System.out.println("Shuttin Down Server");
                EmployeeServiceServer.this.stop();
            }

        });

        server.awaitTermination();

    }

    private void stop() {
        if (server != null) {
            server.isShutdown();
        }
    }

}

Below is the log from but when I ping it, I get nothing.

Listening on Port 9000

My client is throwing this error as well:

Exception in thread "main" io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
    at io.grpc.stub.ClientCalls.toStatusRuntimeException(ClientCalls.java:233)
    at io.grpc.stub.ClientCalls.getUnchecked(ClientCalls.java:214)
    at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:139)
    at com.base.services.EmployeeServiceGrpc$EmployeeServiceBlockingStub.getBadgebyNumber(EmployeeServiceGrpc.java:373)
    at com.base.client.Client.sendMetaData(Client.java:66)
    at com.base.client.Client.main(Client.java:37)
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: localhost/0:0:0:0:0:0:0:1:9000

Answer 1

I have faced the same error. The reason being grpc server didn't start.

Server server = ServerBuilder.forPort(port).useTransportSecurity(certificate, key).addService(serverServiceDefinition)
            .build().start();

I had written start method as chain to build. To make it work i had to call start() method separately.

server.start();

This solved the error for me.

PS: I'm writing this answer as the above solution didn't clarify much and had to research alot before finding the solution. Hope this will be helpful for other developers.