The system-backup interface

system-backup provides read-only access to the system via /var/lib/snapd/hostfs. This interface gives privileged access to system data.

Auto-connect: no
Transitional: no

Requires snapd version 2.43+.

By design, snaps using strict and devmode confinement run with a different root filesystem than the host. Snaps that implement a backup function, however, need access to the host’s snap-related files outside of this confinement, and this is where the system-backup interface can help.

The system-backup interface provides read-only access to files under the following location:

  • /var/lib/snapd/hostfs

With the following exceptions:

  • /var/lib/snapd/hostfs/dev
  • /var/lib/snapd/hostfs/proc
  • /var/lib/snapd/hostfs/sys

Importantly, neither snapd nor this interface provide any mechanisms to ensure the system is in a ready state for backups. Reliable backup strategies with snaps utilising this interface will need to account for this themselves.

This is a snap interface. See Interface management and Supported interfaces for further details on how interfaces are used.

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