start.js

'use strict'

const path = require('path')
const fs = require('fs')
const logger = require('./app/utils/logger')(__filename)
const throng = require('throng')
const server = require('./server')
const pidFile = path.join(__dirname, '/.start.pid')
const fileOptions = { encoding: 'utf-8' }
let pid

logger.info(`[process.version=${process.version}] [NODE_VERSION=${process.env.NODE_VERSION}]`)

/**
 * throng is a wrapper around node cluster
 * https://github.com/hunterloftis/throng
 */
function start () {
  throng({
    workers: process.env.NODE_WORKER_COUNT || 1,
    master: startMaster,
    start: startWorker
  })
}

/**
 * Start master process
 */
function startMaster () {
  logger.info(`Master started. PID: ${process.pid}`)
  process.on('SIGINT', () => {
    logger.info(`Master exiting`)
    process.exit()
  })
}

/**
 * Start cluster worker. Log start and exit
 * @param  {Number} workerId
 */
function startWorker (workerId) {
  server.start()

  logger.info(`Started worker ${workerId}, PID: ${process.pid}`)

  process.on('SIGINT', () => {
    logger.info(`Worker ${workerId} exiting...`)
    process.exit()
  })
}

/**
 * Make sure all child processes are cleaned up
 */
function onInterrupt () {
  pid = fs.readFileSync(pidFile, fileOptions)
  fs.unlink(pidFile)
  process.kill(pid, 'SIGTERM')
  process.exit()
}

/**
 * Keep track of processes, and clean up on SIGINT
 */
function monitor () {
  fs.writeFileSync(pidFile, process.pid, fileOptions)
  process.on('SIGINT', onInterrupt)
}

monitor()

start()