habitica/website/server/index.js

'use strict';
/* eslint-disable global-require, no-process-env */

// Register babel hook so we can write the real entry file (server.js) in ES6
// In production, the es6 code is pre-transpiled so it doesn't need it
if (process.env.NODE_ENV !== 'production') {
  require('babel-register');
}

// Initialize configuration BEFORE anything
const setupNconf = require('./libs/setupNconf');
setupNconf();
const nconf = require('nconf');

const IS_PROD = nconf.get('IS_PROD');
const STACKDRIVER_TRACING_ENABLED = nconf.get('ENABLE_STACKDRIVER_TRACING') === 'true';
if (IS_PROD && STACKDRIVER_TRACING_ENABLED) {
  require('@google-cloud/trace-agent').start(); // eslint-disable-line global-require
}

const cluster = require('cluster');
const logger = require('./libs/logger');

const IS_DEV = nconf.get('IS_DEV');
const CORES = Number(nconf.get('WEB_CONCURRENCY')) || 0;

// Setup the cluster module
if (CORES !== 0 && cluster.isMaster && (IS_DEV || IS_PROD)) {
  // Fork workers. If config.json has WEB_CONCURRENCY=x, use that - otherwise, use all cpus-1 (production)
  for (let i = 0; i < CORES; i += 1) {
    cluster.fork();
  }

  cluster.on('disconnect', function onWorkerDisconnect (worker) {
    let w = cluster.fork(); // replace the dead worker

    logger.info('[%s] [master:%s] worker:%s disconnect! new worker:%s fork', new Date(), process.pid, worker.process.pid, w.process.pid);
  });
} else {
  module.exports = require('./server.js');
}