Rsnapshot

rsnapshot is a filesystem backup utility based on rsync. Using rsnapshot, it is possible to take snapshots of your filesystems at different points in time. Using hard links, rsnapshot creates the illusion of multiple full backups, while only taking up the space of one full backup plus differences. When coupled with ssh, it is possible to take snapshots of remote filesystems as well. This document is a tutorial in the installation and configuration of rsnapshot.

Installation

To install rsnapshot:

apk add rsnapshot

Configuration

To configure rsnapshot, copy the example configuration /etc/rsnapshot.conf.default to /etc/rsnapshot.conf, and edit it to your needs based on the comments and the official documentation. Note that rsnapshot requires tabs between options and values in rsnapshot.conf; this is done such that spaces can be included in filenames without requiring any extra escaping or quoting.

The most important parts to modify are where to store the backups:

snapshot_root	/mnt/backup

How many backups to retain:

retain	daily	7
retain	weekly	4
retain	monthly	12

And what to backup:

# Local
backup	/home/			local/
backup	/etc/			local/

# Remote
backup	user@remote:/home/user/	remote/		exclude=/home/user/Downloads

In this case, every 7th daily backup is saved as a weekly backup, every 4th weekly backup is retained as a monthly backup, and every 12th monthly backup is deleted. The folders /home and /etc from the local machine are backed up to /mnt/backup/local/, while it uses ssh to back up the folder /home/user on the machine remote to /mnt/backup/remote/. Make sure that root has password-less ssh-access to the machines you want to backup over the internet (i.e. run ssh-keygen and ssh-copy-id as root). The last line also shows an example of how you can exclude parts of the location from backups.

Testing

To test that your config file has the correct syntax:

rsnapshot configtest

To check what the system would do when running a backup without executing the commands:

rsnapshot -t daily
rsnapshot -t weekly
rsnapshot -t monthly

Finally, perform the first backup:

rsnapshot daily

The last part might take a while, so grab a cup of tea and a biscuit. Subsequent backups should be much faster, as it will then only have to copy files that has actually changed since last backup.

Automation

After setting up and testing rsnapshot as described above, the next step is to make cron automatically run rsnapshot for us at fixed intervals. The easiest way to achieve this, is to create a few scripts in the folders /etc/periodic/* that crond monitors:

Contents of /etc/periodic/daily/rsnapshot

#!/bin/sh exec /usr/bin/rsnapshot daily

Contents of /etc/periodic/weekly/rsnapshot

#!/bin/sh exec /usr/bin/rsnapshot weekly

Contents of /etc/periodic/monthly/rsnapshot

#!/bin/sh exec /usr/bin/rsnapshot monthly

Remember to make the scripts executable:

chmod +x /etc/periodic/*/rsnapshot

After that, test that the scripts work as expected:

run-parts /etc/periodic/daily
run-parts /etc/periodic/weekly
run-parts /etc/periodic/monthly

Assuming crond is set to start at boot (the default), your system should now take backups automatically.