CD
Cloudflare Developers•2mo ago
Gary, el Pingüino Artefacto

Caching for Workers

Hi, I set up a custom and simple worker to allow access for public files but deny access for user uploaded files. 
export default {
  async fetch(request, env, ctx): Promise<Response> {
    const url = new URL(request.url)
    const key = url.pathname.slice(1)

    if (request.method !== "GET") {
      return new Response("Method not allowed", { status: 405 })
    }

    if (!key) {
      return new Response("No key provided", { status: 400 })
    }

    const cache = caches.default
    const cacheKey = new Request(url.toString(), request)
    const cachedResponse = await cache.match(cacheKey)
    if (cachedResponse) {
      return cachedResponse
    }

    if (key.startsWith("uploads")) {
      return new Response("Uploaded files are not available for download", { status: 404 })
    }

    const object = await env.BUCKET.get(key)
    if (!object) {
      return new Response("Not found", { status: 404 })
    }

    const headers = new Headers()
    object.writeHttpMetadata(headers)
    headers.set("etag", object.httpEtag)
    headers.set("Content-Type", object.httpMetadata?.contentType ?? "application/octet-stream")
    headers.set("Content-Length", object.size.toString())
    headers.set("Cache-Control", "public, max-age=3600")
    headers.set("Vary", "Accept-Encoding")

    const response = new Response(object.body, { headers })
    ctx.waitUntil(cache.put(cacheKey, response.clone()))
    return response
  },
} satisfies ExportedHandler<Env>
export default {
  async fetch(request, env, ctx): Promise<Response> {
    const url = new URL(request.url)
    const key = url.pathname.slice(1)

    if (request.method !== "GET") {
      return new Response("Method not allowed", { status: 405 })
    }

    if (!key) {
      return new Response("No key provided", { status: 400 })
    }

    const cache = caches.default
    const cacheKey = new Request(url.toString(), request)
    const cachedResponse = await cache.match(cacheKey)
    if (cachedResponse) {
      return cachedResponse
    }

    if (key.startsWith("uploads")) {
      return new Response("Uploaded files are not available for download", { status: 404 })
    }

    const object = await env.BUCKET.get(key)
    if (!object) {
      return new Response("Not found", { status: 404 })
    }

    const headers = new Headers()
    object.writeHttpMetadata(headers)
    headers.set("etag", object.httpEtag)
    headers.set("Content-Type", object.httpMetadata?.contentType ?? "application/octet-stream")
    headers.set("Content-Length", object.size.toString())
    headers.set("Cache-Control", "public, max-age=3600")
    headers.set("Vary", "Accept-Encoding")

    const response = new Response(object.body, { headers })
    ctx.waitUntil(cache.put(cacheKey, response.clone()))
    return response
  },
} satisfies ExportedHandler<Env>
But for every time a request is made, a worker runs. I'm trying to cache the file for 1 hour to avoid the invocation but it doesn't seems to work. Enabling public access via a custom domain isn't an option because I don't want user uploaded to be accessed. Thanks 🙂
4 Replies
Walshy
Walshy•2mo ago
Workers run before cache So while you can fetch from cache in the Worker, the Worker will still be invoked.
Gary, el Pingüino Artefacto
Gary, el Pingüino ArtefactoOP•2mo ago
Is there any work around for this instead? Like a custom cache rule or magic header?
Walshy
Walshy•2mo ago
No, Workers will always run before cache. I'd probably recommend splitting out your public stuff to your non-public stuff and enabling public access on the public stuff. Or you can pay for the invocations, Workers is cheap luckily so it wouldn't cost much (if anything depending on the traffic)
Gary, el Pingüino Artefacto
Gary, el Pingüino ArtefactoOP•2mo ago
Got it, thanks 😄 10 million included in the plan is more than enough and managing 2 different buckets and changing a lot of code is not something I'm willing to do right now

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