What do you have URL_CONFIGURATION set to?

On my URL configuration I have in my local this:

URL_CONFIGURATION=0.0.0.0:3000

I don't know if it's works yet, because if I remove the URL_CONFIGURATIONstill works. Just to add I have this two services running

You would need to use the private domain to connect one service to another.

So my configuration would be in this way:API Gateway configuration:

    ClientsModule.register([
      {
        name: AUTH_SERVICE,
        transport: Transport.GRPC,
        options: {
          url: process.env.PRIVATE_DOMAIN_API_GATEWAY,
          package: AUTH_PACKAGE_NAME,
          protoPath: join(__dirname, '../auth.proto'),
        },
      },
    ]),

Auth Microservice:

  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AuthModule,
    {
      transport: Transport.GRPC,
      options: {
        url: process.env.PRIVATE_DOMAIN_API_GATEWAY,
        protoPath: join(__dirname, '../auth.proto'),
        package: AUTH_PACKAGE_NAME,
      },
    },
  );

This configuration is ok? Or I need to change something?

You would need to use each others private domain, in that configuration you are using the services own private domain.

Oh ok. So the configuration would be this:API Gateway configuration:

    ClientsModule.register([
      {
        name: AUTH_SERVICE,
        transport: Transport.GRPC,
        options: {
          url: process.env.PRIVATE_DOMAIN_AUTH_MICROSERVICE,
          package: AUTH_PACKAGE_NAME,
          protoPath: join(__dirname, '../auth.proto'),
        },
      },
    ]),

Auth Microservice (remains the same, just to make me sure haha):

  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AuthModule,
    {
      transport: Transport.GRPC,
      options: {
        url: process.env.PRIVATE_DOMAIN_API_GATEWAY,
        protoPath: join(__dirname, '../auth.proto'),
        package: AUTH_PACKAGE_NAME,
      },
    },
  );

Thank you for your quick responses!

What do you have those two variables set to?

I have configurated this variables on both this servicesPRIVATE_DOMAIN_API_GATEWAY = grpc-nestjs.railway.internalPRIVATE_DOMAIN_AUTH_MICROSERVICE = grpc-micro.railway.internal

I tried this changes but didn't work yet

They're URLs, so I would assume you need a port and maybe a scheme.

I should generate public URLs and use them in the enviorment variables?

No, you should be using the private network, the URLs are missing ports as I've mentioned.

How do I know the port of the services?In my ApiGateway I set the port but in the microservice don't.I see the provided variables and don't see the port.

I'm not sure where the confusion is coming from, you mentioned a port in your original post, the port you need to use would be the port you have the other service running on.

Oh ok.I got confused because I assume that the port that you refer it was on my microservice.So my code of my microservice is this:

  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AuthModule,
    {
      transport: Transport.GRPC,
      options: {
        url: `${process.env.PRIVATE_DOMAIN_API_GATEWAY}:${process.env.PORT}`,
        protoPath: join(__dirname, '../auth.proto'),
        package: AUTH_PACKAGE_NAME,
      },
    },
  );

Or maybe we can connect on Discord?

You need to use the port that the API gateway runs on, this is a URL after all and your trying to connect your microservice to the API gateway.

I made this change on my microservice:

async function bootstrap() {
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AuthModule,
    {
      transport: Transport.GRPC,
      options: {
        url: `${process.env.PRIVATE_DOMAIN_API_GATEWAY}:${process.env.PORT}`,
        protoPath: join(__dirname, '../auth.proto'),
        package: AUTH_PACKAGE_NAME,
      },
    },
  );
  await app.listen();
}

And my enviorments variables I configured this (image 1)And I got an error (image 2)What should I do?