Economical append-only offsite backups with restic and Wasabi on Debian 10

This guide shows how to install and configure the free backup software restic on Debian Buster to store off-site backups at the cloud storage company Wasabi. The main advantage of this guide is that it provides obligatory append-only backups. This means that once a backup has been made, it is secure in the sense that it cannot be overwritten or erased from the system the backup was made from.