You can set attributes either globally in your Carrierwave config -
CarrierWave.configure do |config|
config.fog_attributes = {'Content-Disposition' => ...}
end
or you can define it on the uploader class itself
def fog_attributes
{'Content-Disposition' => ...}
end
and the method on the uploader can use data accessible to the uploader to determine the appropriate return value for fog_attributes