mirror

# File activestorage/lib/active_storage/service/mirror_service.rb, line 59
    def mirror(key, checksum))
      instrument :mirror, key: key, checksum: checksum do
        if (mirrors_in_need_of_mirroring = mirrors.select { |service| !service.exist?(key) }).any?
          primary.open(key, checksum: checksum) do |io|
            mirrors_in_need_of_mirroring.each do |service|
              io.rewind
              service.upload key, io, checksum: checksum
            end
          end
        end
      end
    end