Cloudflare workers static preset

[cosbgn]

Would be great to get a nitro preset for the new Cloudflare workers with static assets (released yesterday)
https://developers.cloudflare.com/workers/static-assets

Thanks for Nitro, is one of the best projects out there!

[pi0]

Thanks for sharing it. We are investigating the possibility of supporting new static assets handling for cloudflare-worker preset during the beta availability. (PS: also doing benchmark assessments)

In the meantime, Nitro cloudflare-worker preset already allows serving static assets with the current binding format and still benefiting from 3x faster KV that announced!

[RihanArfan]

I've been researching the various Cloudflare Nitro presets from both Nitro and Cloudflare, to see how static assets can be supported.

Existing presets

• Nitro (https://github.com/unjs/nitro/blob/v2/src/presets/cloudflare/preset.ts)
  • cloudflare_worker (alias cloudflare) (Worker Sites, Service Worker, legacy/deprecated)
  • cloudflare_module (Worker Sites, Module)
  • cloudflare_pages (Pages, Static Assets)
• Cloudflare
  • Experimental Nuxt (Worker Sites, Service Worker, Static Assets)

Nitro's cloudflare(_workers) and cloudflare_module preset both use Worker Sites (getAssetFromKV() from cloudflare/kv-asset-handler, now deprecated by CF in favour of Static Assets). The difference is the cloudflare preset is deprecated as it's the legacy service worker format.

• https://github.com/unjs/nitro/blob/v2/src/presets/cloudflare/runtime/cloudflare-worker.ts#L32-L39
• https://github.com/unjs/nitro/blob/v2/src/presets/cloudflare/runtime/cloudflare-module.ts#L40-L58

Cloudflare's preset has a wrangler.toml which adds the Static Assets binding to the public directory, but it extends Nitro's cloudflare(_worker) service worker preset. This means, static assets are correctly served, and any static asset misses would invoke the worker (Nitro), but Nitro will then try and check KV first (which won't exist) before moving on to process the request.

# wrangler.toml
name = "cloudflare-static-assets"
compatibility_date = "2024-09-25"
main = "./dist/worker/index.js"
assets = { directory = "./dist/public", binding = "ASSETS" }

Supporting in Nitro properly

So Nitro can support Static Assets already, but on top of legacy Worker Sites within it's presets. I think these are the options for Nitro:

1. Simply remove the code to handle static assets. Cloudflare will route requests
   • I'm not sure whether requests originating internally from Nitro would work, therefore option 2 might be better
2. Replace Worker Sites part to make a request to the static asset binding.
   • Requests originating from a client to a Nitro endpoint (non static) would result in the static asset being checked twice (by Cloudflare then Nitro)
   • Then requests to static assets from ofetch inside Nitro would resolve correctly? - I believe Nitro does this but need to confirm

It'd also just need the --assets flag added to Wrangler instead of --site inside <preset>.commands[].

We should keep not_found_handling as none. This is so when the Worker queryes ASSETS.fetch(), we don't falsey get a hit. If we get a 404 from the asset binding in the Worker, we can proceed to fetch from Nitro's routes and it can handle 404 if there's no page.

Cloudflare preset

I think Cloudflare's Nitro preset should extend cloudflare_module instead and I may open a PR to do this. I can see why their template exists, as it adds nitro-cloudflare-module and wrangler.toml. It also changes things to match their default (dist/worker/index.js) instead of index.mjs), so their CLI can be used without extra flags/options passed.

[Barbapapazes]

As I understand examples, every assets will hit the server anyway: https://developers.cloudflare.com/workers/static-assets/binding/#runtime-api-reference. Or am I missing something? Documentation is not clear because this page could be interpreted differently (https://developers.cloudflare.com/workers/static-assets/routing/)

[RihanArfan]

Based on the routing page, I believe a positive hit on a static asset means the worker isn't triggered. Like Pages, I think it's just possible to query the ASSETS binding from the worker, but I don't think it means every request goes through a worker first.

However, In Cloudflare Pages with advanced mode (what Nitro uses, _worker.js), it seems like every request invokes the Worker first to allow the Worker to handle middleware etc. https://developers.cloudflare.com/pages/functions/advanced-mode/ Although, Nitro doesn't do anything special and will just first query assets and return them if found on Pages. https://github.com/unjs/nitro/blob/v2/src/presets/cloudflare/runtime/cloudflare-pages.ts#L46-L49

Which means besides losing free unlimited _redirects and _headers with Pages, running Nitro on Workers would be cheaper as requests to static assets doesn't cost a worker invocation.

[pi0]

Moving to nitrojs/nitro#2764