server.js

const fs = require('fs')
const path = require('path')
const express = require('express')
const resolve = file => path.resolve(__dirname, file)
const { createBundleRenderer } = require('vue-server-renderer')

const isProd = process.env.NODE_ENV === 'production'
const app = express()

function createRenderer (bundle, options) {
  // https://github.com/vuejs/vue/blob/dev/packages/vue-server-renderer/README.md#why-use-bundlerenderer
  return createBundleRenderer(bundle, Object.assign(options, {
    // recommended for performance
    runInNewContext: false
  }))
}

let renderer
let readyPromise
const templatePath = resolve('./src/index.template.html')
if (isProd) {
  // In production: create server renderer using template and built server bundle.
  // The server bundle is generated by vue-ssr-webpack-plugin.
  const template = fs.readFileSync(templatePath, 'utf-8')
  const bundle = require('./dist/vue-ssr-server-bundle.json')
  // The client manifests are optional, but it allows the renderer
  // to automatically infer preload/prefetch links and directly add <script>
  // tags for any async chunks used during render, avoiding waterfall requests.
  const clientManifest = require('./dist/vue-ssr-client-manifest.json')
  renderer = createRenderer(bundle, {
    template,
    clientManifest
  })
} else {
  // In development: setup the dev server with watch and hot-reload,
  // and create a new renderer on bundle / index template update.
  readyPromise = require('./build/setup-dev-server')(
    app,
    templatePath,
    (bundle, options) => {
      renderer = createRenderer(bundle, options)
    }
  )
}

app.use('/dist', express.static('./dist'))
app.use('/public', express.static('./public'))

async function render (req, res) {
  res.setHeader('Content-Type', 'text/html')
  try {
		const html = await renderer.renderToString({ url: req.url, hostname: req.hostname })
    res.send(html)
	} catch (err) {
		if (err.url) {
      res.redirect(err.url)
    } else if(err.code === 404) {
      res.status(404).send('404 | Page Not Found')
    } else {
      // Render Error Page or Redirect
      res.status(500).send('500 | Internal Server Error')
      console.error(`error during render : ${req.url}`)
      console.error(err.stack)
    }
	}
}

app.get('*', isProd ? render : (req, res) => {
  readyPromise.then(() => render(req, res))
})

const port = process.env.PORT || 3000
app.listen(port, () => {
  console.log(`server started at localhost:${port}`)
})