I think it would be nice to have a configuration parameter which specifies file names to be present in the data directory, which indicate if a restore of the data is necessary or not.

The backup should utilize the same library for creating archives as already used at a different part of the code base. Library is called github.com/mholt/archiver/v3.

Please also add an integration test for this.

Probably it's even enough to just copy over the files to backup because the sidecar will compress the backup directory anyway.

This new option should also be added to the README.md.