Pseudo Code

• get source folder and the destination folder from settings
• recursively loop over only directories within the source folder and add them to a list
• do the following for each subdirectory
  • create a destination folder name based on source directory
  • get all keys for files in s3 for the destination folder (this can be done in parallel to speed up the listobjects call since it limits to 1000keys)
  • if keys don't exist no comparison needed
    • loop over all files
    • compress (optionally encrypt) and upload file
  • if keys exist we need to compare files
    • loop over all files
    • compare file last modified timestamp with object's last modified time
    • possibly add size check as well using gzip header size
    • compress (optionally encrypt) and upload file