====== Example for using rsnapshot-zfs-helper with rsnapshot-backup ======

**CAVEAT : WORK IN PROGRESS**

==== preface ====

I'm using ''rsnapshot-backup'' which is basically a wrapper around rsnapshot.

It uses one setup per system to backup with one config, exclude and script file.
There are also individual backup and logging directories.
There is a scheduler which parallelizes backup runs and a configuration frontend
using template files to create the backup jobs.

There is also an enabling mechnism using symlinks.

A typical backup job configuration (created with ''rsnapshot-backup-conf'') consists of:

<code>
/etc/rsnapshot-backup.d/conf.<BACKUP-CLIENT>
/etc/rsnapshot-backup.d/exclude.<BACKUP-CLIENT>
/etc/rsnapshot-backup.d/script.<BACKUP-CLIENT>    # optional
/etc/rsnapshot-backup.d/enabled/conf.<BACKUP-CLIENT> -> ../conf.<BACKUP-CLIENT>

/backup/hosts/<BACKUP-CLIENT>/daily.0/
/backup/hosts/<BACKUP-CLIENT>/zfs-snapshots -> daily.0/.zfs/snapshot

/var/log/rsnapshot-backup/<BACKUP-CLIENT>/

<ZPOOL>/backup/hosts/<BACKUP-CLIENT> # ZFS filesystem mounted on /backup/hosts/<BACKUP-CLIENT>/daily.0/
</code>

This example has been created using Debian 9.3 .

==== Setup ====

Inside ''/etc/rsnapshot-backup.d/conf.template'':

<code>
cmd_cp        /bin/true
cmd_preexec   /usr/sbin/rsnapshot-zfs-helper /etc/rsnapshot-backup.d/enabled/conf.<HOST> preexec
cmd_postexec  /usr/sbin/rsnapshot-zfs-helper /etc/rsnapshot-backup.d/enabled/conf.<HOST> postexec
</code>
**Do NOT replace '''<HOST>''' in the section above!** (It's a placeholder used by the template engine.)

Inside ''/etc/rsnapshot-backup.d/conf'':

<code>
storage_backend=zfs_snapshots
zfs_helper=/usr/sbin/rsnapshot-zfs-helper
zfs_zpool=<ZPOOL>
zfs_dataset_prefix=backup/hosts/
</code>
** No leading slash - but a trailing one! **

To create a backup job run:
<code>
rsnapshot-backup-conf <HOSTNAME> <IP>
ssh-copy-id <IP>
rsnasphot-backup-enable <HOSTNAME>
</code>
==== Details ====

This is what ''rsnapshot-backup-conf'' takes care of:

The template mechanism creates:
<code>
/etc/rsnapshot-backup.d/conf.<BACKUP-CLIENT>
/etc/rsnapshot-backup.d/exclude.<BACKUP-CLIENT>
/etc/rsnapshot-backup.d/script.<BACKUP-CLIENT>    # optional
/etc/rsnapshot-backup.d/enabled/conf.<BACKUP-CLIENT> -> ../conf.<BACKUP-CLIENT>

/backup/hosts/<BACKUP-CLIENT>/daily.0/
/backup/hosts/<BACKUP-CLIENT>/zfs-snapshots -> daily.0/.zfs/snapshot

/var/log/rsnapshot-backup/<BACKUP-CLIENT>/

<ZPOOL>/backup/hosts/<BACKUP-CLIENT> # ZFS filesystem mounted on /backup/hosts/<BACKUP-CLIENT>/daily.0/
</code>

The zfs filesystem dataset is created:
<code>
zfs create <ZPOOL>/backup/hosts/<BACKUP-CLIENT> -o compression=lz4 -o snapdir=hidden -o xattr=sa -o acltype=posixacl -o mountpoint=/backup/hosts/<BACKUP-CLIENT>/daily.0
</code>

rsnapshot-zfs-helper is to be configured inside rsnapshot's configuration files. i.e. '''/etc/rsnapshot-backup.d/conf.<BACKUP-CLIENT>'''

Additionally, '''cmd_cp''' has to be set to '''/bin/true''' - so the "cp -al ..." is rendered harmless:

<code>
cmd_cp        /bin/true
cmd_preexec   /usr/sbin/rsnapshot-zfs-helper /etc/rsnapshot-backup.d/enabled/conf.<BACKUP-CLIENT> preexec
cmd_postexec  /usr/sbin/rsnapshot-zfs-helper /etc/rsnapshot-backup.d/enabled/conf.<BACKUP-CLIENT> postexec
</code>

''rsnapshot-backup'' itself handles the promotion of the backup's rotation to the subsequent
rotation levels.