server.ts

import compression from "compression"
import express from "express"
import morgan from "morgan"

import path from "path"

import { createRequestHandler } from "@remix-run/express"

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]
    }
  }
}