SvelteKit and adapter-node -> production

Question

Curious what others are doing with SvelteKit adapter-node builds to put them into production.

For example...

• Serving pre-compressed files
• Setting a cache TTL
• Maybe something like helmet

Is it better to define an entryPoint for the adapter like a server.js that implements polka/express/connect like this...

// src/server.js
import { assetsMiddleware, prerenderedMiddleware, kitMiddleware } from '../build/middlewares.js'
import polka from 'polka'
import compression from 'compression'
import helmet from 'helmet'

const app = polka()

app.use(helmet())
app.use(assetsMiddleware, prerenderedMiddleware, kitMiddleware)
app.use(compression())

app.listen(3000)

or is it better to implement similar functionality in the handler() method of hooks.js?

Interested to know what people are doing to go from a build via adapter-node to production.

Answer 1

After examining what adapter-node generates in the build folder, I decided to set the entryPoint property for the adapter's options in svelte.config.js to ./src/server.mjs which gets added to the build. The handle() method in hooks.js/ts doesn't allow for any control over the static content.

In the code below, I set a redirect for non-https and use helmet to beef up security.

// /src/server.mjs
import polka from 'polka'
import helmet from 'helmet'
import { assetsMiddleware, prerenderedMiddleware, kitMiddleware } from '../build/middlewares.js'

const { PORT = 3000, DOMAIN } = process.env

const isHttpPerHeroku = (req) =>
    req.headers['x-forwarded-proto'] &&
    req.headers['x-forwarded-proto'] !== 'https'

polka()
  // On Heroku (only), redirect http to https
  .use((req, res, next) => {
    if (isHttpPerHeroku(req)) {
      let url = `${DOMAIN}${req.url}`
      let str = `Redirecting to ${url}`
      res.writeHead(302, {
        Location: url,
        'Content-Type': 'text/plain',
        'Content-Length': str.length
      })
      res.end(str)
    } else next()
  })

  // Apply all but two helmet protections
  .use(helmet({
    contentSecurityPolicy: false, // override below
    referrerPolicy: false // breaks "Sign in with Gooogle"
  }))

  // Set the Content Security Policy on top of defaults
  .use(helmet.contentSecurityPolicy({
    useDefaults: true,
    directives: {
      scriptSrc: [
        "'self'",
        `'unsafe-inline'`,
        'https://accounts.google.com/gsi/',
        'https://assets.braintreegateway.com/web/',
        'https://platform.twitter.com/',
        'https://www.google-analytics.com/',
        'https://www.google.com/recaptcha/',
        'https://www.googletagmanager.com/',
        'https://www.gstatic.com/recaptcha/'
      ],
      connectSrc: [
        "'self'",
        'https://accounts.google.com/gsi/',
        'https://api.sandbox.braintreegateway.com/merchants/',
        'https://api.braintreegateway.com/merchants/',
        'https://origin-analytics-sand.sandbox.braintree-api.com/',
        'https://payments.sandbox.braintree-api.com/',
        'https://payments.braintree-api.com/',
        'https://stats.g.doubleclick.net/',
        'https://www.google-analytics.com/',
        'https://platform.twitter.com/',
        'https://assets.braintreegateway.com/web/',
        'https://www.googletagmanager.com/',
        'https://www.google.com/recaptcha/',
        'https://www.gstatic.com/recaptcha/',
        'https://fonts.gstatic.com/',
        'https://client-analytics.braintreegateway.com/'
      ],
      childSrc: [
        "'self'",
        'https://accounts.google.com/gsi/',
        'https://assets.braintreegateway.com/web/',
        'https://platform.twitter.com/',
        'https://syndication.twitter.com/i/jot',
        'https://www.google.com/maps/',
        'https://www.google.com/recaptcha/'
      ],
      fontSrc: [
        "'self'",
        'https:',
        'data:',
        'https://fonts.gstatic.com'
      ],
      imgSrc: [
        "'self'",
        'data:',
        'https://www.google-analytics.com/',
        'https://www.googletagmanager.com/',
        'www.w3.org/2000/svg',
      ],
      frameSrc: [
        'https://accounts.google.com/gsi/',
        'https://www.google.com/recaptcha/',
        'https://platform.twitter.com/',
        'https://assets.braintreegateway.com/web/',
        'https://www.google.com/maps/',
        'https://syndication.twitter.com/i/jot'
      ],
      workerSrc: [
        "'self'"
      ]
    }
  }))

  // Load the SvelteKit build
  .use(assetsMiddleware, prerenderedMiddleware, kitMiddleware)

  // Listen on the appropriate port
  .listen(PORT)