We use Amazon S3 for a good portion of our media hosting. It’s a simple and cost effective solution for serving up assets big and small. When we moved initially to Drupal 6.x ( about a year ago ) I wanted to be sure that we would use S3 for as many of our assets as possible. This tactic was partly inspired by wanting to keep the Drupal codebase nice and clean, and also to allow us to scale horizontally if needed ( multiple app servers behind a load balancer ).
So in an attempt to streamline workflows, we modified this amazon_s3 Drupal module a little. The idea was to allow authors to easily use the Drupal node editor to upload their images and PDFs directly to our S3 bucket. It would also rewrite the URLs to pull the content from our CloudFront CDN. It also sorts your images into folders based on the date ( a-la-Wordpress).
I’ve opened sourced that code now which is simply a fork of the amazon_s3 module. It works pretty well on Drupal 6.x. It has an issue where it uploads assets with some incorrect meta-data. It’s really only a problem for uploaded PDFs where the files will download but won’t open in your browser. This has to do with the S3 metadata tag of application/octet-stream vs. application/pdf. All in all I think its a pretty useful module.
As we move towards migrating to Drupal 7, I have been doing some more research about serving assets via S3 and CloudFront. Additionally, it seems that the Drupal community have developed some new modules which should help streamline a few things
As of a couple years ago Amazon’s CloudFront CDN allows you to use a custom origin. This is really great as you can simply tell it to pull from your own domain rather than an S3 bucket.
So for example, I set this blog up with a CloudFront distribution that pulls direct from http://labs.cooperhewitt.org. The resultant distribution is at http://d2y3kexd1yg34t.cloudfront.net. If you go to that URL you should see a mirror of this site. Then all we have to do is install a plugin for WordPress to replace static asset URLs with the CloudFront URL. You might notice this in action if you inspect the URL of any images on the site. You can of course add a CNAME to make the CloudFront URL prettier, but it isn’t required.
On the Drupal end of things, there is a simple module called CDN that does the same thing as we are doing here via the WordPress W3TC plugin. It simply replaces static asset files with your CloudFront domain. Additionally, I see there is now a new Drupal module called amazons3 ( note the lack of the underscore ). This module is designed to allow Drupal to replace it’s default file system with your S3 bucket. So, when a user uploads files through the Drupal admin interface ( which normally sends files to sites/default/files on your local server ) files automatically wind up in your S3 bucket.
I haven’t gotten this to work as of yet, but I think it’s a promising approach. Using this setup, you could maintain a clean and scalable Drupal codebase, keeping all of your user uploaded assets on an S3 bucket without much change to the standard workflow within the Drupal backend. NICE!