Systemd / udev offline backup script

97-offline_backup.rules

ACTION=="add", ENV{ID_PART_ENTRY_UUID}=="0b8e6986-ec09-8e44-b31f-38e944220a66", TAG+="systemd", ENV{SYSTEMD_WANTS}="offline-backup-connected.service"

README.md

Purpose

Script to copy a backup to external usb harddrive for a 3-2-1+ backup strategy.
The USB disk being disconnected most of the time make it secure for remote attacks.

Tested on debian 12

udev rules is located at /usr/lib/udev/rules.d/97-offline_backup.rules

0b8e6986-ec09-8e44-b31f-38e944220a66 is the partition ID, it can be get by ls -l /dev/disk/by-uuid/

systemd file is located at /usr/lib/systemd/system/offline-backup-connected.service

shell script is located at /root/scripts/on_usb_connected.sh (chould be owned by root:root and chmod 700)

offline-backup-connected.service

[Unit]
Description=USB Connected - Offline backup

[Service]
Type=oneshot
ExecStart=/root/scripts/on_usb_connected.sh
User=root
Group=root

[Install]
WantedBy=multi-user.target

on_usb_connected.sh

#!/bin/bash

DEST=@SLACK_USERNAME
TOKEN=SLACK_TOKEN
VENDOR_ID=aaaa # from lsusb
PRODUCT_ID=aaaa # from lsusb
MOUNT_TARGET=/mnt
PART_UUID=XXXX-XXXXX-XXXX-XXXX # from /usr/bin/lsblk --list --output NAME,FSSIZE,FSTYPE,FSUSED,FSUSE%,FSVER,UUID,GROUP,LABEL,TYPE,VENDOR

sendMessage () {
  /usr/bin/curl -H 'Content-Type: application/json' -d '{"text": "'"$1"'", "channel": "'$DEST'"}' -H "Authorization: Bearer $TOKEN" -X POST https://slack.com/api/chat.postMessage -q > /dev/null 2>&1
}

sync () {
  /usr/bin/rsync -avP -e 'ssh -i /root/scripts/id_rsa_backup' user@SERVER:/remoteLocation  $MOUNT_TARGET/backups/
  result=$?

  if [[ "$result" != "0" ]]; then
    sendMessage "An error occurred while doing rsync..."
  else
    sleep 5
    /usr/bin/umount $MOUNT_TARGET
    sendMessage "Done. USB Can be disconnected."
  fi
}

# sendMessage "Test 1"


res=$(/usr/bin/lsusb -d $VENDOR_ID:$PRODUCT_ID)
found=$?

if [[ "$found" != "0" ]]; then
  /usr/bin/echo "USB Device not detected"
  exit -1
else
  /usr/bin/echo "USB Device detected"
fi

DEVICES=$(/usr/bin/lsblk --list --output NAME,FSSIZE,FSTYPE,FSUSED,FSUSE%,FSVER,UUID,GROUP,LABEL,TYPE,VENDOR | grep $PART_UUID)
MATCHING_PART=$(/usr/bin/echo "$DEVICES" | cut -d\   -f1)

if [[ "$MATCHING_PART" == "" ]]; then
  /usr/bin/echo "Part not found"
  exit -1
fi

if /usr/bin/mountpoint -q "$MOUNT_TARGET"; then
  /usr/bin/echo "Already mounted"
else
  /usr/bin/echo "Mounting..."
  /usr/bin/mount -o rw,noatime,compress=no /dev/$MATCHING_PART $MOUNT_TARGET
fi

/usr/bin/echo "File system mounted !"

DEVICES=$(/usr/bin/lsblk --list --output UUID,FSSIZE,FSTYPE,FSUSED,FSUSE% | grep $PART_UUID)
USED=$(/usr/bin/echo $DEVICES | cut -d\  -f4)
TOTAL=$(/usr/bin/echo $DEVICES | cut -d\  -f2)
USED_PERCENT=$(/usr/bin/echo $DEVICES | cut -d\  -f5)

/usr/bin/echo "Usage : $USED / $TOTAL ($USED_PERCENT)"
/usr/bin/echo "Starting sync"

sendMessage "File system mounted \nUsage : $USED / $TOTAL ($USED_PERCENT) \nStarting offline copy..."

sync