paperclip-aws is a full featured storage module that supports all S3 locations (American, European and Japanese) without any additional hacking.

• supports US, European and Japanese S3 instances;
• supports both http and https urls;
• supports expiring urls;
• supports different permissions for each Paperclip style;
• can generate urls for read, write и delete operations;
• correctly sets content-type of uploaded files;
• ability to set content-disposition of uploaded files;
• supports amazon server side encryption (thanks to pvertenten);
• highly compatible with included in Paperclip S3 storage module

• paperclip ~> 2.4
• aws-sdk >= 1.2.0

gem install paperclip-aws

After this add 'paperclip-aws' to your Gemfile or environment.rb

class SomeS3Attachment < ActiveRecord::Base
  def self.s3_config
    @@s3_config ||= YAML.load(ERB.new(File.read("#{Rails.root}/config/s3.yml")).result)[Rails.env]    
  end

  has_attached_file :data,
                    :styles => {
                      :thumb => [">75x"],
                      :medium => [">600x"]
                    },                    
                    :storage => :aws,
                    :s3_credentials => {
                      :access_key_id => self.s3_config['access_key_id'],
                      :secret_access_key => self.s3_config['secret_access_key'],
                      :endpoint => self.s3_config['endpoint']
                    },
                    :bucket => self.s3_config['bucket'],                    
                    :s3_host_alias => self.s3_config['s3_host_alias'],
                    :s3_permissions => :public_read,
                    :s3_protocol => 'http',
                    :s3_options => {
                      :sse => 'AES256',
                      :storage_class => :reduced_redundancy,
                      :content_disposition => 'attachment'
                    },
                    
                    :path => "company_documents/:id/:style/:data_file_name"  
                    
  # You also can modify @s3_options hash directly.
  before_save do
    self.data.s3_options[:content_disposition] = "attachment; filename=#{self.data_file_name}"
    self.data.s3_options[:sse] = true if self.confidential_information?
    self.data.s3_options[:storage_class] = true if self.unimportant_information?
  end                          
end

Create link for file that will expire in 10 seconds after it was created. Useful when redirecting user to file.

file.data.url(:original, { :expires => Time.now + 10.seconds, :protocol => 'https' })

Endpoint where your bucket is located. Default is 's3.amazonaws.com' which is for 'US Standard' region.

You can find full list of endpoints and regions here

Sets permissions to your objects. Values are:

:private
:public_read
:public_read_write
:authenticated_read
:bucket_owner_read
:bucket_owner_full_control

You can setup permnissions globally for object or per style:

:s3_permissions => :public_read


:s3_permissions => {
  :thumb => :public_read,
  :medium => :authenticated_read,
  :default => :authenticated_read
}

Default protocol to use: 'http' or 'https'.

Hash of additional options. Available options are:

• :sse – 'AES256' (the only available encryption now)
• :storage_class – :standard (default) or :reduced_redundancy
• :content_disposition

'paperclip-aws' redefines Paperclip url method to get object URL.

def url(style=default_style, options={})
end

Supported options are:

• :protocol — 'http' or 'https'

  Use this options to redefine default protocol, configured in model.

• :expires

  Sets the expiration time of the URL; after this time S3 will return an error if the URL is used. This can be an integer (to specify the number of seconds after the current time), a string (which is parsed as a date using Time#parse), a Time, or a DateTime object. This option defaults to one hour after the current time.

  Default is set to 3600 seconds.

• :action

  Method, the HTTP verb or object method for which the returned URL will be valid. Valid values:

  • :get or :read
  • :put or :write
  • :delete

  Default is set to :read, which is the most common used.

Yes, usage of paperclip-aws is confirmed by several rather big projects:

• www.sdelki.ru
• www.lienlog.com (opens for public in December 2011)
• www.sharypic.com (soon)

I hope that it is used in a lot of other projects, if you know them – let me know.