Dynamic50 Web Design and Development, Ruby on Rails Specialists in London and Oxford, UK

Amazon Cloudfront is a great way of serving your assets for your site from localised buckets.

Firstly you need to set up a new distribution from your amazon CloudFront console here.

Associate your distribution with a current bucket, or alternatively with a new bucket name, but if you do this you will need to create the bucket on your s3 account so it is associated with it. I have created a new one and called it d50-assets

Enter your cname values, you will need 4 for the standard cnames with Rails assets. Mine are:

assets0.dynamic50.com
assets1.dynamic50.com
assets2.dyanmic50.com
assets3.dynamic50.com

And create the distribution….

When the distribution is created you will be assigned a domain name for you distribution. In my case this is d1i6gs7snlaxix.cloudfront.net
So now your DNS server needs to be configured for your domain. In my case this is from within my slicehost console.

I set the following as CNAMES:

assets0.dynamic50.com
assets1.dynamic50.com
assets2.dyanmic50.com
assets3.dynamic50.com

with a value of :

my_unique_cloudfront_domain.cloudfront.net

If you are on slicehost, don’t forget the full stop (.) after the value so it doesn’t auto-complete to

my_unique_cloudfront_domain.cloudfront.net.yourhost.com

Using an s3 access tool (I use s3fox), log in to you s3 account and upload all of your assets (ie everything inside your public directory) to the bucket.

Make sure the bucket permissions are set correctly so that it is world readable.

Now you are ready to make the changes on your Rails app.

Go to the production environment file and set:

ActionController::Base.asset_host = "http://assets%d.myhost.com"

cap deploy and your asset host will be working!

On a side note, I don’t want my javascripts or css served by this asset host, so to turn this off replace the above line with the following line:

ActionController::Base.asset_host = Proc.new { |source|
  unless source.starts_with?('/stylesheets' || '/javascripts')
    "http://assets#{rand(4)}.myhost.com"
  end
}