Midnight Oil

I’ve recently added a patch to attachment_fu that allows for serving out your S3-stored files via Amazon CloudFront. So, if you want an instant CDN, it doesn’t get much easier.

(Note: For Paperclip users, check out this writeup on intridea)

Get the plugin

Get the latest version of attachment_fu from github.

script/plugin install git://github.com/technoweenie/attachment_fu.git

Setup CloudFront

You’ll need to sign up for CloudFront. It’s as simple to join as any of the other AWS’s.

Once you’re signed up, you’ll need to create what are called distributions. These are essentially mappings from S3 buckets to CloudFront domains. You can use the command-line API if you want, but I found it easiest to just use S3Fox.

In S3Fox, find the S3 bucket that you want to serve out, right click, and choose Manage Distributions. You will see a screen like the one below:

Give the distribution a comment, make sure enable is checked, and click on Create Distribution. It will be InProgress for a few minutes, so just keep refreshing. Once it transitions to Deployed, you’re done!

Configuration

We’ve added one new option to the amazon_s3.yml file that comes with attachment_fu, distribution_domain. Copy the Resource Url (something like http://XXXXX.cloudfront.net) from S3Fox and enter it in your amazon_s3.yml file as the distribution_domain. Make sure to only get the domain and strip off the ‘http://’

Next, you’ll need to update all your has_attachment models that you wish to serve out. For each of these, add a cloudfront option like so:

class MyClass
has_attachment(
:content_type => :image,
:storage => :s3,
:cloudfront => true,
:max_size => 1.megabytes,
:processor => "Rmagick"
)
end

You’re Done!

That’s it! Now, everywhere you use myobj.public_filename, it will use the CloudFront domain and serve it through the CDN.

Bonus Points: CNAME

If you think the XXXX.cloudfront.net domain is ugly, you can set a CNAME on the distribution and do some DNS monkey-business to choose your own CNAME. I’ll do this at some point (and update this blog post), but so far it hasn’t been important to me.