Question

I’ve been developing a new web application which relies on Amazon S3 servers as storage system, and Codeiginter as the PHP framework.

I need to force the file to download when the link is clicked. The original URL looks like this:

http://www.our-web.com/download/do/1.jpg

which generates a temporary signed URL to the actual file on the Amazon S3 servers like this:

http://main_bucket.s3.amazonaws.com/post/1/1.jpg?AWSAccessKeyId=AKIAJEOQKYPKC3CCU5RA&Expires=1305395426&Signature=iuzCdA22gImLK192%2BMAhk8OkAY8%3D

I need to make the file start downloading from the real Amazon URL it soon as the user clicks the link.

I have two ways now to do so:

1. Use redirect() which will open the file not download it; or

2. Alter headers as this code:

   header('Content-type: application/force-download');
   header('Content-Disposition: attachment; filename=' . $file_name);
   header('Content-Transfer-Encoding: binary');
   header('Expires: 4000');
   header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
   header('Pragma: public');
   header('Content-Length: ' . filesize($generated_file));
   
   readfile($generated_file);
   

Unfortunately, both ways don’t help me. The second method causes the download to come from my website and not from directly from Amazon.

How can I force the file to download directly from the Amazon S3 servers, and not from my website?

Answer 1

You just need to set the correct headers on your files in S3 in order to force the browser to download rather than opening the file. Set these:

Content-Disposition: attachment; filename=FILENAME.EXT
Content-Type: application/octet-stream

You will need to set them when uploading the files to S3. With the php SDK you’d use create_object.

Or you can set these after uploading using ‘change_content_type’ or by copying the file to itself in S3 and setting the correct headers.