paperclip_multi_env_s3_cname_hack.rb

# this allows you to use a CNAME for multiple environments
# Paperclip only supports multiple access, secret access and bucket

# in your model...

  has_attached_file :attachment,
    :path => ":class/:id/:style_:basename.:extension",
    :storage => :s3,
    :s3_credentials => "#{RAILS_ROOT}/config/s3.yml",
    :s3_host_alias => YAML.load_file("#{RAILS_ROOT}/config/s3.yml")[RAILS_ENV]["s3_host_alias"],
    :url => ":s3_alias_url"

# in config/s3.yml

  development:
    bucket: development_assets.my_company_domain.com
    access_key_id: XXXXXXXXXXXXX
    secret_access_key: XXXXXXXXXXXXXXXXX
    s3_host_alias: development_assets.my_company_domain.com
  
  test:
    bucket: test_assets.my_company_domain.com
    access_key_id: XXXXXXXXXXXXX
    secret_access_key: XXXXXXXXXXXXXXXXX
    s3_host_alias: test_assets.my_company_domain.com

  production:
    bucket: assets.client_domain.com
    access_key_id: XXXXXXXXXXXXX
    secret_access_key: XXXXXXXXXXXXXXXXX
    s3_host_alias: assets.client_domain.com