index.js

'use strict'
const cluster = require('cluster')
const assert = require('assert')
const util = require('util')
const os = require('os')
const PrettyError = require('pretty-error')

process.env.NODE_ENV = process.env.NODE_ENV || 'development'
process.env.NODE_CLUSTER = process.env.NODE_CLUSTER || process.env.WEB_CONCURRENCY // heroku
process.env.DEBUG = process.env.DEBUG || 'app*'
process.env.HOST = process.env.HOST || '0.0.0.0'
process.env.PORT = process.env.PORT || 1331

global.pe = new PrettyError()
pe.skipNodeFiles()
pe.skipPackage('babel-cli')
pe.skipPackage('promise')
pe.skipPackage('bluebird')
pe.skipPackage('express')
pe.start()

global.debug = require('debug')
debug.enable(process.env.DEBUG)

debug('app master')('env', util.inspect({
    NODE_ENV: process.env.NODE_ENV,
    NODE_CLUSTER: process.env.NODE_CLUSTER,
    HOST: process.env.HOST,
    PORT: process.env.PORT
}, false, null, true))

const clusterEnabled = /true|[1-9]+(?:[0-9]+)?/.test(process.env.NODE_CLUSTER)

if (clusterEnabled && cluster.isMaster) {
    const concurrency = /true/.test(process.env.NODE_CLUSTER) ? os.cpus().length : parseInt(process.env.NODE_CLUSTER)

    for (let i = 0; i < concurrency; i++) {
        const host = '0.0.0.0'
        const port = process.env.PORT // if different ports: parseInt(process.env.PORT) + i
        const env = {
            HOST: host,
            PORT: port
        }

        debug('app master')('fork', i, env)

        cluster.fork(env)
    }

    cluster.on('exit', (worker, code, signal) => {
        debug('app master')('exit', `Worker ${worker.process.pid} died`)
    })

    process.on('uncaughtException', (err) => {
        debug('app master')('error', `uncaughtException`, pe.render(err))

        // handleError(err)
    })

    process.on('unhandledRejection', (err) => {
        debug('app master')('error', `unhandledRejection`, pe.render(err))

        // handleError(err)
    })

    process.on('beforeExit', (code) => {
        debug('app master')('event', `beforeExit`, code)
    })

    process.on('exit', (code) => {
        debug('app master')('event', `exit`, code)
    })

    process.on('SIGINT', () => {
        debug('app master')('signal', `SIGINT`)
    })

} else {
    // require('babel-register')
    require('./server')
}

package.json

{
  "name": "GuessBrand-Redirect",
  "version": "0.1.0",
  "main": "index.js",
  "scripts": {
    "clean": "rm -rf build && mkdir build",
    "start": "./node_modules/.bin/cross-env NODE_ENV=production NODE_CLUSTER=true ./node_modules/.bin/babel-node index.js",
    "start-nf": "./node_modules/.bin/cross-env NODE_ENV=production NODE_CLUSTER=true ./node_modules/.bin/nf start",
    "start-pm2": "./node_modules/.bin/cross-env NODE_ENV=production NODE_CLUSTER=true ./node_modules/.bin/pm2 start",
    "start-dev": "./node_modules/.bin/cross-env NODE_ENV=development NODE_CLUSTER=false ./node_modules/.bin/babel-watch index.js",
    "build": "npm run clean && ./node_modules/.bin/cross-env NODE_ENV=production NODE_CLUSTER=true ./node_modules/.bin/babel index.js server.js -d build",
    "serve": "./node_modules/.bin/cross-env NODE_ENV=production NODE_CLUSTER=true node build/index.js",
    "test": "./node_modules/.bin/cross-env NODE_ENV=test NODE_CLUSTER=false mocha --compilers js:babel-register",
    "postinstall": "npm run build"
  },
  "engines": {
    "node": "^6.0.0"
  },
  "dependencies": {
    "babel-cli": "^6.16.0",
    "babel-preset-es2015": "^6.16.0",
    "babel-preset-stage-0": "^6.16.0",
    "babel-register": "^6.16.3",
    "cross-env": "^3.1.3",
    "debug": "^2.2.0",
    "express": "^4.14.0",
    "foreman": "^2.0.0",
    "http-status": "^0.2.3",
    "morgan": "^1.7.0",
    "pm2": "^2.0.18",
    "pretty-error": "^2.0.2"
  },
  "devDependencies": {
    "babel-eslint": "^7.0.0",
    "babel-watch": "^2.0.3",
    "chai": "^3.5.0",
    "eslint": "^3.8.1",
    "mocha": "^3.1.2"
  }
}

server.js

'use strict'
import cluster from 'cluster'
import assert from 'assert'
import util from 'util'
import express from 'express'
import morgan from 'morgan'
import status from 'http-status'

if (typeof pe === 'undefined') {
    const PrettyError = require('pretty-error')
    const pe = new PrettyError()
    pe.skipNodeFiles()
    pe.skipPackage('babel-cli')
    pe.skipPackage('promise')
    pe.skipPackage('bluebird')
    pe.skipPackage('express')
    pe.start()
}

if (typeof debug === 'undefined') {
    const debug = require('debug')
    debug.enable(process.env.DEBUG || 'app*')
}

assert.ok(process.env.PORT, 'process.env.PORT')
assert.ok(process.env.HOST, 'process.env.HOST')

debug('app server')('env', util.inspect({
    NODE_ENV: process.env.NODE_ENV,
    HOST: process.env.HOST,
    PORT: process.env.PORT
}, false, null, true))

const app = express()

app.set('workerId', cluster.worker ? ` ${cluster.worker.id}` : '')

app.use(morgan('dev'))

app.get('/', (req, res) => {
    debug(`app server${app.get('workerId')}`)(`GET /`, `url`, req.query.url)

    if (req.query.url) {
        res.redirect(req.query.url)

    } else {
        res.set('Content-Type', 'text/plain')
        res.end(`Specify \`url\` param for redirect.`)
    }
})

app.use((req, res, next) => {
    let err = new Error(status[404])

    // err.level = 'info'
    // err.request = req
    // err.response = res

    // debug(`app server${app.get('workerId')}`)('error', err.level, pe.render(err))

    // handleError(err)

    res.set('Content-Type', 'text/plain')
    res.status(404).end(`${404} ${status[404]}`)
})

app.use((err, req, res, next) => {
    debug(`app server${app.get('workerId')}`)('error', err)

    // err.level = 'critical'
    // err.request = req
    // err.response = res

    // debug(`app server${app.get('workerId')}`)('error', err.level, pe.render(err))

    // handleError(err)

    res.set('Content-Type', 'text/plain')
    res.status(res.status || 500).end(`${res.status || 500} ${status[res.status || 500]}`)
})

app.listen(parseInt(process.env.PORT), process.env.HOST, () => {
    debug(`app server${app.get('workerId')}`)
        ('listen', `Worker${app.get('workerId')} listening on ${process.env.HOST}:${process.env.PORT}`)
})

test.js

'use strict'
import http from 'http'
import assert from 'assert'
import chai from 'chai'

process.env.PROTOCOL = `http`
process.env.HOST = `localhost`
process.env.PORT = 1331
process.env.NODE_ENV = 'test'

// import '../index'
// import '../server'

require('../index')
// require('../server') // BUG: when using `import '../server'` the `process.env.*` variables are not passed. =S

const endpoint = `${process.env.PROTOCOL}://${process.env.HOST}:${process.env.PORT}`

describe('GET /', () => {

    it('should return status 200', done => {
        http.get(`${endpoint}/`, res => {
            assert.equal(200, res.statusCode)
            done()
        })
    })

    it('should return status 404', done => {
        http.get(`${endpoint}/undefined`, res => {
            assert.equal(404, res.statusCode)
            done()
        })
    })

})