Cloudflare worker that downloads files from R2 bucket

cloudflare-r2-download-worker.js

import jwt from '@tsndr/cloudflare-worker-jwt'

// Add following config to wrangler.toml
//
// r2_buckets = [
//   { binding = "STORAGE_BUCKET", bucket_name = "your_bucket_name" }
// ]
//
// Also requires download_jwt_secret in the worker env

export default {
  async fetch(request, env, ctx) {
    const url = new URL(request.url)
    const jwt_secret = env.download_jwt_secret
    const token = url.searchParams.get('token')

    // for me to test if the worker is hosted fine.
    if (url.searchParams.get('x') == "test") {
      return new Response('Hello World!');
    }

    if (!token) {
      return new Response('Unauthorized', { status: 401 })
    }

    try {
      // 1. Verify JWT
      const verifiedToken = await jwt.verify(token, jwt_secret)
      if (!verifiedToken) {
        return new Response('Invalid token', { status: 401 })
      }

      // 2. Extract file information
      const fileKey = verifiedToken.payload.fileKey

      // 3. Fetch object from R2
      let object = await env.STORAGE_BUCKET.get(fileKey)
      if (object === null) {
        return new Response('Object not found', { status: 404 })
      }

      // 4. Set Cache-Control headers
      const headers = new Headers()
      headers.set('Cache-Control', 'public, max-age=3600') // Cache for 1 hour
      headers.set('Content-Type', object.httpMetadata.contentType)

      return new Response(object.body, {
        headers: headers,
      })
    } catch (error) {
      return new Response('Error: ' + error.message, { status: 500 })
    }
  },
}