server.ts

import { createRequestHandler } from '@remix-run/express'
import compression from 'compression'
import express from 'express'
import morgan from 'morgan'
import path from 'path'

const app = express()

app.use((req, res, next) => {
	// helpful headers:
	res.set('x-fly-region', process.env.FLY_REGION ?? 'unknown')
	res.set('Strict-Transport-Security', `max-age=${60 * 60 * 24 * 365 * 100}`)

	// /clean-urls/ -> /clean-urls
	if (req.path.endsWith('/') && req.path.length > 1) {
		const query = req.url.slice(req.path.length)
		const safepath = req.path.slice(0, -1).replace(/\/+/g, '/')
		res.redirect(301, safepath + query)
		return
	}
	next()
})

// if we're not in the primary region, then we need to make sure all
// non-GET/HEAD/OPTIONS requests hit the primary region rather than read-only
// Postgres DBs.
// learn more: https://fly.io/docs/getting-started/multi-region-databases/#replay-the-request
app.all('*', function getReplayResponse(req, res, next) {
	const { method, path: pathname } = req
	const { PRIMARY_REGION, FLY_REGION } = process.env

	const isMethodReplayable = !['GET', 'OPTIONS', 'HEAD'].includes(method)
	const isReadOnlyRegion =
		FLY_REGION && PRIMARY_REGION && FLY_REGION !== PRIMARY_REGION

	const shouldReplay = isMethodReplayable && isReadOnlyRegion

	if (!shouldReplay) return next()

	const logInfo = {
		pathname,
		method,
		PRIMARY_REGION,
		FLY_REGION,
	}
	console.info(`Replaying:`, logInfo)
	res.set('fly-replay', `region=${PRIMARY_REGION}`)
	return res.sendStatus(409)
})

app.use(compression())

// http://expressjs.com/en/advanced/best-practice-security.html#at-a-minimum-disable-x-powered-by-header
app.disable('x-powered-by')

// Remix fingerprints its assets so we can cache forever.
app.use(
	'/build',
	express.static('public/build', { immutable: true, maxAge: '1y' }),
)

// Everything else (like favicon.ico) is cached for an hour. You may want to be
// more aggressive with this caching.
app.use(express.static('public', { maxAge: '1h' }))

app.use(morgan('tiny'))

const MODE = process.env.NODE_ENV
const BUILD_DIR = path.join(process.cwd(), 'build')

app.all(
	'*',
	MODE === 'production'
		? createRequestHandler({ build: require(BUILD_DIR) })
		: (...args) => {
				purgeRequireCache()
				const requestHandler = createRequestHandler({
					build: require(BUILD_DIR),
					mode: MODE,
				})
				return requestHandler(...args)
		  },
)

const port = process.env.PORT || 3000

app.listen(port, () => {
	// require the built app so we're ready when the first request comes in
	require(BUILD_DIR)
	console.log(`✅ app ready: http://localhost:${port}`)
})

function purgeRequireCache() {
	// purge require cache on requests for "server side HMR" this won't let
	// you have in-memory objects between requests in development,
	// alternatively you can set up nodemon/pm2-dev to restart the server on
	// file changes, we prefer the DX of this though, so we've included it
	// for you by default
	for (const key in require.cache) {
		if (key.startsWith(BUILD_DIR)) {
			// eslint-disable-next-line @typescript-eslint/no-dynamic-delete
			delete require.cache[key]
		}
	}
}