Cloudflare Worker 搭配 Backblaze B2

cf-worker-b2.js

'use strict';
const b2Domain = ''; //你要在Cloudflare上綁定的Backblaze網域
const b2Bucket = ''; //Backblaze B2的存儲桶名稱
const b2UrlPath = `/file/${b2Bucket}/`;
addEventListener('fetch', event => {
 return event.respondWith(fileReq(event));
});

// define the file extensions we wish to add basic access control headers to
const corsFileTypes = ['png', 'jpg', 'gif', 'jpeg', 'webp'];

// backblaze returns some additional headers that are useful for debugging, but unnecessary in production. We can remove these to save some size
const removeHeaders = [
 'x-bz-content-sha1',
 'x-bz-file-id',
 'x-bz-file-name',
 'x-bz-info-src_last_modified_millis',
 'X-Bz-Upload-Timestamp',
 'Expires'
];
const expiration = 31536000; // override browser cache for images - 1 year

// define a function we can re-use to fix headers
const fixHeaders = function(url, status, headers){
 let newHdrs = new Headers(headers);
 // add basic cors headers for images
 if(corsFileTypes.includes(url.pathname.split('.').pop())){
 newHdrs.set('Access-Control-Allow-Origin', '*');
 }
 // override browser cache for files when 200
 if(status === 200){
 newHdrs.set('Cache-Control', "public, max-age=" + expiration);
 }else{
 // only cache other things for 5 minutes
 newHdrs.set('Cache-Control', 'public, max-age=300');
 }
 // set ETag for efficient caching where possible
 const ETag = newHdrs.get('x-bz-content-sha1') || newHdrs.get('x-bz-info-src_last_modified_millis') || newHdrs.get('x-bz-file-id');
 if(ETag){
 newHdrs.set('ETag', ETag);
 }
 // remove unnecessary headers
 removeHeaders.forEach(header => {
 newHdrs.delete(header);
 });
 return newHdrs;
};
async function fileReq(event){
 const cache = caches.default; // Cloudflare edge caching
 const url = new URL(event.request.url);
 if(url.host === b2Domain && !url.pathname.startsWith(b2UrlPath)){
 url.pathname = b2UrlPath + url.pathname;
 }
 let response = await cache.match(url); // try to find match for this request in the edge cache
 if(response){
 // use cache found on Cloudflare edge. Set X-Worker-Cache header for helpful debug
 let newHdrs = fixHeaders(url, response.status, response.headers);
 newHdrs.set('X-Worker-Cache', "true");
 return new Response(response.body, {
 status: response.status,
 statusText: response.statusText,
 headers: newHdrs
 });
 }
 // no cache, fetch image, apply Cloudflare lossless compression
 response = await fetch(url, {cf: {polish: "lossless"}});
 let newHdrs = fixHeaders(url, response.status, response.headers);

  if(response.status === 200){

    response = new Response(response.body, {
      status: response.status,
      statusText: response.statusText,
      headers: newHdrs
    });
  }else{
    response = new Response('找不到檔案!', { status: 404 })
  }

 event.waitUntil(cache.put(url, response.clone()));
 return response;
}