Add clustering via $WEB_CONCURRENCY env var

Procfile

@@ -1 +1 @@
-web: node lib/server/start.js
+web: node lib/server

Procfile.local

@@ -1 +1 @@
-web: NODE_ENV=development node -r ./modules/register.js modules/server/start.js
+web: NODE_ENV=development node -r ./modules/register.js modules/server

modules/server/index.js

@@ -1,10 +1,14 @@
+/*eslint-disable no-console*/
+import path from 'path'
 import cors from 'cors'
+import throng from 'throng'
 import morgan from 'morgan'
 import express from 'express'
 import devErrorHandler from 'errorhandler'
 import WebpackDevServer from 'webpack-dev-server'
 import { createRequestHandler } from 'npm-http-server'
 import { staticAssets, assetsCompiler, createDevCompiler } from './AssetsUtils'
+import webpackConfig from '../../webpack.config'
 import { sendHomePage } from './MainController'
 import { logStats } from './StatsUtils'
 
@@ -23,7 +27,7 @@ export const createRouter = (config = {}) => {
 
 const errorHandler = (err, req, res, next) => {
   res.status(500).send('<p>Internal Server Error</p>')
-  console.error(error.stack)
+  console.error(err.stack)
   next(err)
 }
 
@@ -56,9 +60,9 @@ export const createDevServer = (config) => {
       // https://webpack.github.io/docs/node.js-api.html#stats-tojson
       assets: true,
       colors: true,
-      version: false,
-      hash: false,
-      timings: false,
+      version: true,
+      hash: true,
+      timings: true,
       chunks: false
     },
 
@@ -79,3 +83,47 @@ export const createDevServer = (config) => {
 
   return server
 }
+
+const port = process.env.PORT || 5000
+const statsFile = path.resolve(__dirname, '../../stats.json')
+const publicDir = path.resolve(__dirname, '../../public')
+const registryURL = process.env.REGISTRY_URL || 'https://registry.npmjs.org'
+const bowerBundle = process.env.BOWER_BUNDLE || '/bower.zip'
+const redirectTTL = process.env.REDIRECT_TTL || 500
+const autoIndex = !process.env.DISABLE_INDEX
+const redisURL = process.env.REDIS_URL
+
+const DefaultServerConfig = {
+  id: 1,
+  port,
+  webpackConfig,
+  statsFile,
+  publicDir,
+  registryURL,
+  bowerBundle,
+  redirectTTL,
+  autoIndex,
+  redisURL
+}
+
+export const startServer = (serverConfig) => {
+  const config = {
+    ...DefaultServerConfig,
+    ...serverConfig
+  }
+
+  const server = process.env.NODE_ENV === 'production'
+    ? createServer(config)
+    : createDevServer(config)
+
+  server.listen(config.port, () => {
+    console.log('Server #%s listening on port %s, Ctrl+C to stop', config.id, config.port)
+  })
+}
+
+if (require.main === module)
+  throng({
+    start: (id) => startServer({ id }),
+    workers: process.env.WEB_CONCURRENCY || 1,
+    lifetime: Infinity
+  })

modules/server/start.js

@@ -1,32 +0,0 @@
-import path from 'path'
-import { createServer, createDevServer } from './index'
-
-const port = process.env.PORT || 5000
-const webpackConfig = require('../../webpack.config')
-const statsFile = path.resolve(__dirname, '../../stats.json')
-const publicDir = path.resolve(__dirname, '../../public')
-const registryURL = process.env.REGISTRY_URL || 'https://registry.npmjs.org'
-const bowerBundle = process.env.BOWER_BUNDLE || '/bower.zip'
-const redirectTTL = process.env.REDIRECT_TTL || 500
-const autoIndex = !process.env.DISABLE_INDEX
-const redisURL = process.env.REDIS_URL
-
-const serverConfig = {
-  port,
-  webpackConfig,
-  statsFile,
-  publicDir,
-  registryURL,
-  bowerBundle,
-  redirectTTL,
-  autoIndex,
-  redisURL
-}
-
-const server = process.env.NODE_ENV === 'production'
-  ? createServer(serverConfig)
-  : createDevServer(serverConfig)
-
-server.listen(port, () => {
-  console.log('Server started on port %s, Ctrl+C to quit', port)
-})

package.json

@@ -41,6 +41,7 @@
     "redis": "^2.6.0-1",
     "rimraf": "^2.5.2",
     "style-loader": "^0.13.1",
+    "throng": "^4.0.0",
     "webpack": "^1.13.0",
     "webpack-dev-server": "^1.14.1"
   },