class ActiveStorage::Service::MirrorService

def upload(key, io, checksum: nil, **options)

ensure a match when the upload has completed or raise an ActiveStorage::IntegrityError.
Upload the +io+ to the +key+ specified to all services. If a +checksum+ is provided, all services will 
def upload(key, io, checksum: nil, **options)
  each_service.collect do |service|
    io.rewind
    service.upload key, io, checksum: checksum, **options
  end
end