Possible Feature Request/Discussion: Support BackupDisk on local filesystem when Self-hosting

[netcarver]

@pascalbaljet Hi Pascal.

I understand the rationale of preventing backups to the Eddy Server Management host local disk to prevent you ever handling customer backup data for your hosted service. However, for people who are self-hosting Eddy, this might not be problem.

In my case, I host Eddy in a local docker container and being able to backup to local disk via Eddy, without any additional configuration for external services (or the need to expose an S3 facade/local SFTP endpoint) would be nice.