Moving attachment_fu from filesystem to S3 storage

Most of this transition is fairly easy, but many users will find a small hiccup when it comes time to upload your files to S3.

1. Create a config/amazon_s3.yml file with your credentials.
2. Setup your S3 bucket, upload the files (I use S3Fox). Make sure to set the access to world-read for your uploaded files.
3. Add the aws-s3 gem to your environment as well as your hosting platform or server.

Ah, but there is a small problem. How do you get from attachment_fu’s default of 0010/5198/filename.png to 105198/filename.png? The solution is a small Bash script. This is designed to be run from within the top-level folder for each of your attachment_fu directories, like public/pictures, public/avatars, etc.

I’d recommend running this on a copy of your files, just in case I messed up, but the most important line is let "d=$d1$d2". This wonderful line combines the 0010 and 5198 and treats them as a number, for a result of 105198. I don’t know much about let, but it seems to work wonderfully when you need to treat strings as integers.

PS. Don’t forget step 3.