ThomasLeister / lxd-backup

A Python script to back up ZFS based LXD containers via Restic

lxd-backup.py

Mounts all existing ZFS-based LXD container root filesystems and runs Restic on those mountpoints. This script was created for personal use! Don't expect high quality and submit PRs if you improved something :-)

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What this script does

• It connects to the LXD Daemon and asks for a list of all LXD containers
• It makes a ZFS snapshot for every container (Snapshot of the containers /root/ device)
• The snapshot is mounted to /mnt/backup/[containername]
• Restic makes a backup of /mnt/backup
• All the mounts are umounted
• Backup snapshots are deleted
• Restic deletes old Backups
• Restic checks backup repository integrity

Requirements / dependencies

Python3 dependencies are listed in requirements.txt, but can also be installed system-wide via:

apt install \
    python3-pylxd \
    python3-dotenv \
    python3-path

Restic needs to be installed on the system and must be initialized (restic init). Furthermore, the following Restic environment file needs to exist in the same directory as the lxd-backup.py script:

resticenv.sh

#!/bin/bash

export RESTIC_REPOSITORY="sftp:<user>.your-storagebox.de:<hostname>"
export RESTIC_PASSWORD="<passphrase>"

• <user> SFTP user. Here: Hetzner Storage Box User
• <hostname>: Hostname of server for storage subdirectory
• <passphrase>: Restic backup archive passphrase

The type of storage (here: SFTP) can be modified as needed. Restic supports multiple storage backends: https://restic.readthedocs.io/en/stable/030_preparing_a_new_repo.html

Systemd service and timer files

lxd-backup.timer

[Unit]
Description=Restic backup cronjob

[Timer]
OnCalendar=*-*-* 03:00:00
RandomizedDelaySec=900

[Install]
WantedBy=timers.target

• OnCalendar: Makes the backup process run every day at 3 am.
• RandomizeDelaySec: Make the backup start at random times within the 900 seconds margin to reduce sudden loads on systems with multiple backup script instances.

lxd-backup.service

[Unit]
Description=Restic backup

[Service]
Type=simple
User=root
CPUQuota=600%
Environment=PYTHONUNBUFFERED=yes
ExecStart=/usr/bin/python3 /opt/backup/lxd-backup.py

• CPUQuota: Sets CPU quota limit to use for the backup process. 600 % == 6 cores

Put those files into /etc/systemd/system/ and enable them:

systemctl enable --now lxd-backup.timer
systemctl enable lxd-backup.service  

Deleting old backups

The script has a restic forget --prune hardcoded into the source. The retention periods are not yet configurable. If you need to change the values, do it in the source (or create a mechanism to make them configurable and submit a PR ;-) ).