main.js

/* eslint no-console: off */

// http://pm2.keymetrics.io/docs/usage/use-pm2-with-cloud-providers/#heroku-google-app-engine-azure
//

const pm2 = require('pm2');

// Set by Heroku or -1 to scale to max cpu core -1
const instances = process.env.WEB_CONCURRENCY || -1;
const maxMemory = process.env.WEB_MEMORY || 512; // " " "

const DEV_CONFIG = {
  name: 'heroku-line-bot-local',
  script: 'src/index.js',
  env: process.env,
  watch: true,
  interpreter: './node_modules/.bin/babel-node',
};

const PRODUCTION_CONFIG = {
  name: 'heroku-line-bot',
  script: 'build/index.js',
  env: process.env,
  exec_mode: 'cluster',
  instances,
  max_memory_restart: `${maxMemory}M`, // Auto-restart if process takes more than XXmo
};

pm2.connect(() => {
  pm2.start(
    process.env.NODE_ENV === 'production' ? PRODUCTION_CONFIG : DEV_CONFIG,
    err => {
      if (err) {
        console.error('Error while launching applications', err.stack || err);
        return;
      }
      console.log('PM2 and application has been succesfully started');

      // Display logs in standard output
      pm2.launchBus((busErr, bus) => {
        console.log('[PM2] Log streaming started');

        bus.on('log:out', packet => {
          console.log('[App:%s] %s', packet.process.name, packet.data);
        });

        bus.on('log:err', packet => {
          console.error('[App:%s][Err] %s', packet.process.name, packet.data);
        });
      });
    }
  );
});