The following PHP package will be required depending on what you are trying to do.
Save to cloud:
Curl - http://www.php.net/manual/en/book.curl.php
FileInfo - http://www.php.net/manual/en/book.fileinfo.php
Image manipulation:
ImageMagick - http://www.php.net/manual/en/book.imagick.php
This plugin expects that a config/phrails-paperclip.ini in the Phrails project.
It can be empty for use with File type attachments.
We currently only use it with Rackspace Cloud Files. Your File would look something like:
[global]
user = <username>
key = <cloud-resource-key>
[development]
<model-name> = <container-in-the-cloud-resource>
[production]
<model-name> = <container-in-the-cloud-resource>
Under each environment you can have as many = tags as you need.