application.rb

    config.paperclip_defaults = {
      :storage => :fog,
      :fog_credentials => {:provider => "Local", :local_root => "#{Rails.root}/public"},
      :fog_directory => "/public",
      :fog_host => 'localhost:3000'
    }

model.rb

class Artist < ActiveRecord::Base
  has_attached_file :profile_picture,
		:styles => {
			:thumb => "100x100#",
			:small  => "150x150>",
			:medium => "200x200" },
			:path => "artists/:name/profile_:basename_:style.:extension",
			:default_url => "/images/missing.jpg"
	validates_attachment_content_type :profile_picture, :content_type => /\Aimage\/.*\Z/
end