ironbar/bundle.js

const path = require('path');
const {fork} = require('child_process');

const chalk = require('chalk');
const dotenv = require('dotenv');

['.common.env', '.dev.env', '.env'].forEach((filename) => {
  dotenv.config({path: path.join(__dirname, filename)});
});

const services = process.env.SERVICES.split(',');
services.push('gateway');

const longestServiceNameLength = services.reduce((l, r) => {
  return (r.length > l.length) ? r : l;
}, '').length;

let color = 1;
const colors = [
  'redBright', 'greenBright', 'yellowBright', 'blueBright', 'magentaBright',
  'cyanBright', 'whiteBright', 'red', 'green', 'yellow', 'blue', 'magenta',
  'cyan', 'white', 'gray',
];

const children = [];
const childrenOfService = {};

const bundleServices = (process.env.BUNDLE_SERVICES || '').split(',');
const serviceCounts = bundleServices.reduce((l, r) => {
  const [service, count = 1] = r.split(':');
  if (service in l) { l[service] = count; }
  return l;
}, services.reduce((l, r) => {
  l[r] = 1;
  return l;
}, {}));

const cwd = process.cwd();
services.forEach((service) => {
  for (let i = 0; i < serviceCounts[service]; ++i) {
    forkService(service);
  }
});

function forkService(service) {

  const servicePath = path.join(cwd, 'services', service);

  let index;
  const colorizer = chalk[colors[color++]];
  const dresser = (line) => {
    const prefix = colorizer(`${(index + '').padStart(2, '0')} » ${
      service.padEnd(longestServiceNameLength)
    }  |`);
    console.error(`${prefix} ${line}`);
  };
  const logger = (message) => {
    message.split('\n').forEach(dresser);
  };

  const child = fork(servicePath, [], {
    env: Object.assign({
      SOURCE_PATH: servicePath,
    }, process.env),
    stdio: 'pipe',
  });

  const forwardStream = (data) => {
    logger(data.toString('utf8').replace(/\n$/, ''));
  };
  child.stdout.on('data', forwardStream);
  child.stderr.on('data', forwardStream);

  childrenOfService[service] = childrenOfService[service] || [];
  childrenOfService[service].push(child);

  index = children.length;
  logger(`forking...`);
  children.push(child);

  const createChildActions = (child) => {
    const actions = createActions(child);
    return (action) => {
      actions[action.type](action);
    };
  };

  child.on('message', createChildActions(child));
}

function createActions (child) {

  return {

    listening: () => (child.listening = true),

    connect: ({payload: {clientId, service}}) => {

      const candidate = randomService(service);
      if (candidate) {

        candidate.send({
          type: 'connection_from',
          payload: {
            clientId,
            from: children.indexOf(child),
          },
        });

        child.send({
          type: 'connection_to',
          payload: {
            clientId,
            to: children.indexOf(candidate),
          },
        });
      }
      else {

        child.send({
          type: 'connection_error',
          payload: {
            clientId,
          },
        });
      }
    },

    client_send: ({payload}) => {
      children[payload.to].send({
        type: 'server_recv',
        payload: {
          clientId: payload.clientId,
          data: payload.data,
        },
      });
    },

    server_send: ({payload}) => {
      children[payload.to].send({
        type: 'client_recv',
        payload: {
          clientId: payload.clientId,
          data: payload.data,
        },
      });
    },
  };
}

function randomService(service) {

  const candidates = [...childrenOfService[service]];
  while (candidates.length > 0) {
    const index = Math.floor(Math.random() * candidates.length);
    const [candidate] = candidates.splice(index, 1);
    if (candidate.listening) {
      return candidate;
    }
  }
}