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Setting Up Automated Backups with Restic on Debian Linux

This article was created out of a convo with Claude 3.5 Sonnet.

Backups are crucial, but they need to be automated and reliable to be truly effective. In this guide, we'll set up a robust backup system using restic on Debian Linux 12. We'll configure it to back up Docker volumes (/var/lib/docker/volumes), home directories (/home), and system configuration files (/etc), with snapshots every 12 hours and a sensible retention policy. We'll use systemd to schedule our backups, easily audit backups, and manually run a backup job when desired.

Prerequisites

  • Debian 12 (or similar Linux distribution)
  • restic installed (apt install restic)
  • root access or sudo privileges
  • A backup destination (local disk, SFTP server, or S3 bucket)

The Setup Process

We'll create four files to handle our backup system:

  1. A backup script
  2. An environment file for credentials
  3. A systemd service
  4. A systemd timer

Let's build this system piece by piece.

1. Creating the Backup Script

Create a new file at /usr/local/bin/backup-script.sh:

#!/bin/bash

# Exit on error
set -e

# Load environment variables
source /etc/restic-env

# Paths to backup
BACKUP_PATHS="/var/lib/docker/volumes \
             /home \
             /etc"

# Initialize the repository if it doesn't exist
restic snapshots || restic init

# Perform the backup
restic backup $BACKUP_PATHS

# Keep the last 6 snapshots (72 hours worth, given 12-hour frequency)
# Keep 1 snapshot per week for all other snapshots
restic forget --keep-last 6 --keep-weekly 1 --prune

Make the script executable: sudo chmod +x /usr/local/bin/backup-script.sh

2. Setting Up the Environment File

Create /etc/restic-env to store your credentials and configuration:

# Repository location - adjust this to your needs
# Examples:
# export RESTIC_REPOSITORY="sftp:user@host:/srv/restic-repo"
# export RESTIC_REPOSITORY="s3:s3.amazonaws.com/bucket_name"
# export RESTIC_REPOSITORY="/path/to/local/repo"
export RESTIC_REPOSITORY="<YOUR_REPOSITORY_LOCATION>"

# Repository password
export RESTIC_PASSWORD="<YOUR_STRONG_PASSWORD>"

# If using S3:
# export AWS_ACCESS_KEY_ID="<YOUR_ACCESS_KEY>"
# export AWS_SECRET_ACCESS_KEY="<YOUR_SECRET_KEY>"

Secure the environment file: sudo chmod 600 /etc/restic-env

3. Creating the Systemd Service

Create /etc/systemd/system/restic-backup.service:

[Unit]
Description=Restic backup service
After=network.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/backup-script.sh
User=root
Group=root

# Set reasonable security options
ProtectSystem=full
ProtectHome=read-only
PrivateTmp=true
NoNewPrivileges=true

4. Setting Up the Timer

Create /etc/systemd/system/restic-backup.timer:

[Unit]
Description=Run restic backup every 12 hours

[Timer]
OnCalendar=_-_-\* 00,12:00:00
RandomizedDelaySec=1800
Persistent=true

[Install]
WantedBy=timers.target

5. Activating the Backup System

Enable and start the timer:

sudo systemctl daemon-reload
sudo systemctl enable restic-backup.timer
sudo systemctl start restic-backup.timer

Backup Schedule and Retention

This setup:

  • Creates backups every 12 hours (at midnight and noon)
  • Adds a random delay of up to 30 minutes to avoid exact timing
  • Keeps the last 72 hours of backups (6 snapshots)
  • Maintains one weekly backup for older data
  • Automatically prunes old snapshots

Useful Commands

  • Check the timer status: sudo systemctl list-timers restic-backup.timer
  • Run a backup manually: sudo systemctl start restic-backup.service
  • View backup logs: sudo journalctl -u restic-backup.service
  • List all snapshots: sudo bash -c 'source /etc/restic-env; restic snapshots'
  • Restore files: sudo restic restore latest --target /path/to/restoration/directory

Security Considerations

The setup includes several security measures:

  • The environment file is restricted to root access only
  • The systemd service runs with restricted privileges
  • The backup script uses safe bash options
  • File systems are mounted read-only during backups where possible

Testing Your Backups

Remember the cardinal rule of backups - they're only as good as your ability to restore from them. Regularly test your backup restoration process by:

  • Creating a test directory
  • Restoring a backup to it
  • Verifying the restored files

Conclusion

You now have a robust, automated backup system that:

  • Runs automatically every 12 hours
  • Maintains a sensible backup history
  • Includes important system directories
  • Uses secure settings
  • Can be easily monitored and managed

Remember to periodically verify your backups and adjust the retention policy based on your specific needs. Happy backing up!