Blog Post: http://www.railstoolkit.com/posts/rails-amazon-s3-uploader-with-progress-bar-2010-update

Steps to make the example work:

- Make sure you have the bundler gem and install the required gems by running “bundle”

- Add your s3 bucket and keys to config/amazon_s3.yml

- Make sure a public readable crossdomain.xml exists in the s3 bucket you specified in config/amazon_s3.yml, with the following content (you can also limit access to your domain to be more secure):

- Start the application with “bundle exec script/server”

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM
"http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
  <allow-access-from domain="*" secure="false" />
</cross-domain-policy>

- Also make sure a folder named ‘test’ exists in that bucket. Files will be uploaded to that folder.