The Nextcloud AIO container itself doesn’t have access to the backup directory, but it has access to the docker socket (/var/run/docker.sock). Having access to the docker socket means it can perform any docker operation on the host system, in this case starting a separate backup container with the backup directory mounted.
The Nextcloud AIO container itself doesn’t have access to the backup directory, but it has access to the docker socket (
/var/run/docker.sock
). Having access to the docker socket means it can perform any docker operation on the host system, in this case starting a separate backup container with the backup directory mounted.