Stream files from S3 as ZIP file.

stream-s3-as-zip.php

<?php

use Aws\S3\S3Client;
use ZipStream\ZipStream; // https://github.com/maennchen/ZipStream-PHP

protected function streamPhotosetAsZip($files)
{
    $s3 = S3Client::factory('...');
    $zip = new ZipStream("foobar.zip");

    foreach ($files as $file) {
        $request = $s3->createPresignedRequest(
            $s3->getCommand('GetObject', [
                'Key' => $file->path,
                'Bucket' => 'bucket-name',
            ]),
            '+20 seconds'
        );

        $tmpfile = tempnam(sys_get_temp_dir(), str_random());

        (new HttpClient)->request('GET', (string) $request->getUri(), ['sink' => fopen($tmpfile, 'w+')]);

        $fp = fopen($tmpfile, 'r');
        $zip->addFileFromStream(basename($file->path), $fp);

        fclose($fp);
    }

    $zip->finish();
}