Cloudflare Worker that bundles R2 objects in a Zip file

index.ts

import { z } from 'zod';
import { ZipWriter, BlobReader, configure } from '@zip.js/zip.js';

// Without this, we get uncaught error due to Workers runtime bug
// See: https://github.com/gildas-lormeau/zip.js/discussions/514
configure({
	useCompressionStream: false,
});

// Payload schema that lists the files to be bundled, their filenames and the archive filename
const schema = z.object({
	archive_filename: z.string().endsWith('.zip'),
	files: z.array(
		z.object({
			r2key: z.string(),
			filename: z.string(),
		})
	),
});

export default {
	async fetch(request, env, ctx): Promise<Response> {
		const body = await request.json();

		const payload = schema.safeParse(body);
		if (!payload.success) {
			return new Response(JSON.stringify({ status: 'failed', error: payload.error }), {
				status: 409,
				headers: { 'Content-Type': 'application/json' },
			});
		}

		let { readable, writable } = new IdentityTransformStream();

		// Create a ZIP archive stream
		const archive = new ZipWriter(writable);

		// Store all the promises to catch any errors all together later
		let promises: Promise<any>[] = [];

		for (const receipt of payload.data.files) {
			const { r2key, filename } = receipt;

			// Fetch the receipt from the R2 bucket
			const fileContent = await env.STORAGE_BUCKET.get(r2key);
			if (!fileContent) {
				return new Response(`Object not found: ${r2key}`, { status: 404 });
			}

			// Add the receipt to the ZIP archive
			promises.push(archive.add(filename, new BlobReader(await fileContent.blob())));
		}

		promises.push(archive.close());

		Promise.all(promises).catch((err) => {
			console.log(err);
		});

		return new Response(readable, {
			headers: {
				'Content-Type': 'application/zip',
				'Content-Disposition': `attachment; filename="${payload.data.archive_filename}"`,
			},
		});
	},
} satisfies ExportedHandler<Env>;