Rails How to upload precompiled assets to Cloudfront

Question

• I'm using a Rails 3.2 app
• I created a Cloudfront distribution with a S3 origin
• I already change config.action_controller.asset_host to my cloudfront asset
• I'm using capistrano

I want to know, how to upload my precompiled assets to Cloudfront every time I deploy

Answer 1

There is no need for the s3 bucket as Amazon Cloudfront now supports "custom origins". It used to be that you had to specify a s3 bucket as the origin, but now you can point your cloudfront distribution at your rails app.

http://aws.typepad.com/aws/2010/11/amazon-cloudfront-support-for-custom-origins.html

So, after you create a distribution that is pointed at your publicly accessible app, you set your asset host in the appropriate config file e.g. production.rb and you are off to the races.

config.action_controller.asset_host = "url of your cloudfront distribution"

Here is a half decent article on how to configure things:

http://ryantownsend.co.uk/post/13126016608/cloudfront-cdn-on-rails

Don't be confused with the bit about setting up CNAME recprds for an origin subdomain. This is only relevant if you want to use your own subdomain instead of amazons.

Answer 2

After installing the aws-s3 gem, you can add this at this end of your capistrano recipe :

set :cdn_user, "KEY ID" # This is called "CDN KEY API" for AWS
set :cdn_api_key, "YOUR KEY SECRET"
set :cdn_container, "bucket name"

namespace :assets do
    task :to_cdn do
      require 'aws/s3'
      AWS::S3::Base.establish_connection!(:access_key_id => cdn_user, :secret_access_key => cdn_api_key )
      assets_dir = "#{shared_path}/assets"
      Dir.glob(assets_dir + "/**/*").each do |file|
        if !File.directory?(file)
          cdn_filename = file.gsub(assets_dir,"assets")
          AWS::S3::S3Object.store(cdn_filename, open(file) , cdn_container)
        end
      end
    end
end

Using a trigger like this :

after "deploy:assets:precompile", "assets:to_cdn"

You will also need to launch the compilation at some point in your recipe with :

load 'deploy/assets'

Result : at the end of your asset compilation, all your assets are going to be pushed on S3, and you will be able to access them from cloudfront.

You then have to update your config/environment/production.rb to point to your CDN URL.

config.action_controller.asset_host = "http://assets.example.com"

Answer 3

There's a great Ruby gem that handles this called AssetSync. If you combine it with turbo-sprockets, you can make sure that only new or updated assets are copied on deploy.