paperclip.rb

if paperclip_cfg = YAML.load_file("#{Rails.root}/config/paperclip.yml")[Rails.env]
  paperclip_cfg.symbolize_keys!

  Paperclip::Attachment.default_options.merge!(paperclip_cfg)
end

paperclip.yml

common: &local_settings
  path: ":class/:id_partition/:hash.:extension"
  hash_secret: "31f20b780e1e9dec2643bde2fca542ad2ba5140502ce091b364fd35f07168b38829aaeffe3ccfb853ce69f580480323cdf103a18ee092a0be1ec16abb425054b"
  convert_options: {
    all: "-interlace Plane -strip"
  }

development:
  <<: *local_settings
  storage: :filesystem

test:
  <<: *local_settings
  storage: :filesystem

aws_config: &aws_config
  bucket: Rails.application.secrets.bucket
  access_key_id: Rails.application.secrets.aws_access_key_id
  secret_access_key: Rails.application.secrets.aws_access_key_secret

production:
  <<: *local_settings
  storage: :s3
  s3_credentials: *aws_config
  s3_permissions: :private