zfsnapr is a tool for creating recursive system snapshots and mounting the result in a given directory tree:
❯ zfsnapr mount /mnt/snapshot
❯ ls -l /mnt/snapshot
drwxr-xr-x 2 root wheel 48 9 Aug 14:53 bin
drwxr-xr-x 15 root wheel 71 9 Aug 15:37 boot
-r--r--r-- 1 root wheel 6109 9 Aug 14:53 COPYRIGHT
dr-xr-xr-x 2 root wheel 2 23 Oct 2020 dev
...
❯ zfsnapr umount /mnt/snapshot
❯ ls -l /mnt/snapshot
total 0
I use this with BorgBackup to make consistent point-in-time backups without Borg being aware of ZFS - it’s just another directory tree regardless of how the underlying datasets are arranged.
Using --exec, --devfs, --tmpfs and --passthrough it’s also possible to create functional chroot environments within the mounted tree, allowing the migration of existing backup setups without making them aware there even is a special snapshot location to work out of.
I’ve just committed fixes for operation on non-ZFS-on-root systems, so it should Just Work on more setups. You can also now restrict to a given part of the directory tree with --root without it needing to be a mountpoint, so if, say, your /home was canmount=no you can still --root=/home and it’ll mount any datasets within that part of the tree.
zfsnapr is written in Ruby, but has no additional dependencies outside stdlib.