createCloudflareAssetReader

createCloudflareAssetReader({ binding, assets }) is the public file reader for Workers. Meeko's generated wrangler.jsonc declares assets with run_worker_first: true and html_handling/not_found_handling set to "none", so all requests reach the Worker; this reader only responds to paths in the build's asset manifest, reading them from the ASSETS binding, and returns null for all others.

This lets a Worker serve files with the same rules as Node, Bun and Deno: nothing outside the manifest, the same ETag and the same cache policy.

Usage#

import { createCloudflareAssetReader, createWorker } from "@meekojs/meeko/cloudflare";
import type { CloudflareAppContext } from "@meekojs/meeko/cloudflare";

function createCloudflareApp({ env, platform }: CloudflareAppContext<Env>) {
  return createApp({
    production: true,
    platform,
    assets: createCloudflareAssetReader({ binding: env.ASSETS, assets: manifest.assets ?? {} }),
  });
}

export default createWorker(createCloudflareApp);

Type#

function createCloudflareAssetReader(options: CloudflareAssetReaderOptions): AssetReader

interface CloudflareAssetReaderOptions {
	readonly binding: CloudflareAssetsBinding
	readonly assets: AssetManifest
}

interface CloudflareAssetsBinding {
	fetch(request: Request): Promise<Response>
}

interface AssetReader {
	get(pathname: string, request: Request): Promise<Response | null>
}

Parameters#

Return value#

An AssetReader with get(pathname, request): null for a path not in assets or a method other than GET or HEAD; 304 if If-None-Match matches, without reading the binding; 200 with the binding's body, content-type, ETag, content-length and cache-control (immutable for one year for hashed files, max-age=0, must-revalidate for the rest).

Examples#

The output of meeko build --adapter cloudflare#

.meeko/output/cloudflare/
  worker.js            ← createWorker and the room class, a single module
  wrangler.jsonc       ← assets: { directory: "./assets", binding: "ASSETS", run_worker_first: true }
  assets/              ← client build and public/
  assets/_meeko/prerender/  ← prerendered pages, which the Worker reads and never serves as files

Checking that a build file is not public#

curl -s -o /dev/null -w "%{http_code}\n" https://mi-app.example/_meeko/prerender/manifest.json   # 404
curl -s -o /dev/null -w "%{http_code}\n" https://mi-app.example/worker.js                         # 404

Common mistakes#

A listed file missing from assets#

assets/ uploaded without the assets/assets/ directory (a partial deployment)

get rejects with Error: Missing build asset /assets/entry-4f2a.js; the application responds with 500 and sends it to onError. Deploy the complete output folder with wrangler deploy --config .meeko/output/cloudflare/wrangler.jsonc.

npx wrangler deploy --config .meeko/output/cloudflare/wrangler.jsonc

A public/_meeko/#

public/_meeko/logo.svg

The assets' _meeko/ is reserved for prerendered pages: meeko build --adapter cloudflare stops with public/_meeko está reservado para la salida de Cloudflare de Meeko; cámbiale el nombre.

public/brand/logo.svg

Changing assets in server.wrangler#

server: { adapter: "cloudflare", wrangler: { assets: { directory: "./public", not_found_handling: "single-page-application" } } }

meeko build --adapter cloudflare stops with TypeError: server.wrangler.assets is generated by Meeko and cannot be overridden (the same applies to main, no_bundle and find_additional_modules): the Worker must see every request to apply the manifest, sessions and CSP.

server: { adapter: "cloudflare", wrangler: { routes: [{ pattern: "mi-app.example", custom_domain: true }] } }

Notes#

• Security. Paths are looked up in the manifest without decoding, and the URL requested from the binding comes from the manifest key, never from the request.
• Cost. With run_worker_first, each file is a Worker invocation; hashed files carry immutable, and Cloudflare's CDN and the browser cache them for a year.
• CSP and headers (since 1.7). server.headers also applies to these files, except headers they already carry, such as Cache-Control.

Related#

• createWorkerServes a Meeko application from a Cloudflare module Worker, created once per isolate with its bindings, forwarding Socket upgrades to their room's Durable Object.
• createCloudflarePrerenderSourceA Worker's prerendered pages, read from the Static Assets binding once per isolate, with their navigation payload and CSP hashes.
• createNodeAssetReaderServes only build files listed in the asset manifest from disk on Node, using streaming and Meeko's ETag, HEAD, 304 and cache policy.
• Cloudflare WorkersMeeko as a full-stack framework