snapshooter

1 Introduction

snapshooter is a bash script which allows you to create btrfs snapshots and send them incrementally to local or remote locations through ssh. Remote servers can be woken up using Wake-on-LAN. It automatically keeps a configurable number of snapshots.

2 Configuration

All configuration files are by default located in /usr/local/etc/snapshooter/ If you want to change this, edit the configdir variable in the actual script.

2.1 Main configuration file

/usr/local/etc/snapshooter/snapshooter.conf:

# the periods of your snapshots must be set here. These are common examples.
periods=( weekly daily hourly )

# Wake-on-LAN binary which should be used
# This is the default one for arch linux
wol='/bin/wol'

# The default time in seconds which the script should wait
# for the server to be booted. Can be overridden by an individual config.
defaultboottime=120

# if you want to automatically poweroff the remote server, set this to yes
# or override it by an individual config.
poweroffserver='no'

2.2 Configs for creation of snapshots:

/usr/local/etc/snapshooter/create/[configname].conf

The individual config files, for subvolumes, which should be snapshoted follow this syntax:

# name of the subvolume: 'subvol0'
# or with ',' separated names: 'subvol0,subvol1'
# recursive snapshooting is supported, just set name to '*'
name='subvol0'

# if set to yes, the script will search for a subvolume named $name
# in the $snapdir
# if you want to snapshot the snapdir itself, for example /,
# set this to no
recursive='yes'

# directory where the subvolume is located
snapdir='/pool'

# destination of the snapshot, must be on the same physical disk
destination='/pool/snapshots'

# optional prefix and postfix for the snapshot can be set here. 
# for example the hostname of the machine, to avoid confusion, 
# when snapshots of the root filesystem of multiple machines
# are be backed up on one server
prefix='laptop'
postfix='read-only'

# numbers of snapshots, that should be kept.
# Each period must be specified in snapshooter.conf.
weekly=5
daily=6
hourly=3

A snapshot will be named: [prefix]_[name]_[date]_[period]_[postfix]:

laptop_subvol0_2016-07-24_06:00:00_hourly_read-only

2.3 Configs for sending of snapshots:

/usr/local/etc/snapshooter/send/[configname].conf

config file syntax for snapshots which should be sent:

# name of the subvolume: 'subvol0'
# or with ',' separated names: 'subvol0,subvol1'
# recursive snapshooting is supported, just set name to '*'
name='subvol0'

# directory where the snapshots are located.
# this must be the same directory as the destination
# of the corresponding "create config"
snapdir='/pool/snapshots'

# destination, where snapshots should be sent to
destination='/mnt/usb-hdd'

# optional prefix and postfix for the snapshot can be set here. 
# for example the hostname of the machine, to avoid confusion, 
# when snapshots of the root filesystem of multiple machines
# are be backed up on one server
prefix='laptop'
postfix=''

# numbers of snapshots, that should be kept.
# Each period must be specified in snapshooter.conf.
weekly=5
daily=6
hourly=3

# if snapshots should be sent to a remote location
# public key authentification must be set up.
sshlogin='root@destination-server'
# if you use a custom ssh port:
port='xxxxx'

# if the server should be woken up, set the mac address here
mac='XX:XX:XX:XX:XX:XX'
# optional ip address of server
ip='192.168.1.45'

# optionally override the default boot time ( in seconds )
boottime=180

# it the server shoud be shut down, after the sending of snapshots,
# set to yes
poweroffserver='yes'

3 Using the script:

3.1 creating snapshots:

snapshooter create [period]

[period] is one of the periods specified in the main config file, for example daily.

The script will then create daily snapshots for every config in /usr/local/etc/snapshooter/create/ and get rid of old snapshots automatically.

3.2 sending snapshots:

snapshooter send [configname]

[configname] is the name of the config, which will be used. specifying multiple with ',' separated confignames is supported. if you omit the [configname] option, then all confis in /usr/local/etc/snapshooter/send/ will be used.

The script will now determine whether a parent snapshot is present and if not it will bootstrap it. Once it exists it will send the following snapshots incrementally. Old snapshots will be deleted automatically.

4 Automation

The script is supposed be automaticly run using systemd or cron.

https://wiki.archlinux.org/index.php/Systemd/Timers
This article will help you create these units if you do not already know how to write them.

NOTE: The script must be run as root, since the btrfs commands require it.

5 Miscellaneous

Disclaimer: I'm in no way responsible for any damage or dataloss the script may cause, through bugs or incorrect configuration. Use at your own risk.

The script is Provided under a GNU GPLv3 License