https://medium.com/@FloSloot/node-js-protobuf-grpc-and-discovery-services-fd099a3fe51a

anyService.js

const server = require('express')();
const axios = require('axios');
const createClient = require('../client');

// very same thing as in databaseService.js
const serviceDefinition = {
  name: 'anyService',
  ipv4: '127.0.0.1',
  port: 3001
};
// create a new map to store the locations we care about
const serviceLocations = new Map();

// first start the server and
// then register at the discovery service
// then fetch the database service and store it!
server
  .get('/', async  (_, res) => {
    const dbService = serviceLocations.get('databaseService');
    const response = await axios.get(`http://${dbService.ipv4}:${dbService.port}/db`);
    res.send(response.data);
  })
  .listen(serviceDefinition.port, () => console.log(`AnyService listens on port ${serviceDefinition.port}`));

(async () => {
  const client = await createClient();
  await client.register(serviceDefinition);

  const { registrations: [dbService] } = await client.fetchServiceLocation({
    registrations: [{
      name: 'databaseService'
    }]
  });

  serviceLocations.set('databaseService', dbService);
})();