incremental btrfs snapshots sent to remote synology

incremental.sh

#!/bin/env bash

set -e

# This script is used to create incremental snapshots of the given btrfs volume.

# capture today's date
today=$(date +%Y%m%d)
# use yesterday's as base for incremental snapshot
yesterday=$(date -d "yesterday" +%Y%m%d)
# capture the date of 2 days ago for cleanup
twodaysago=$(date -d "2 days ago" +%Y%m%d)

# define the target directory to store snapshots
snapshot_dir="/var/.snapshots/"
target_dir="/volume1/NetBackup/snaps"

# ensure the target directory exists
if [ ! -d "$snapshot_dir" ]; then
    sudo mkdir -p "$snapshot_dir"
fi

# create the snapshot
sudo btrfs subvolume snapshot -r /home /var/.snapshots/home-$today

# send the incremental snapshot
sudo btrfs send -p /var/.snapshots/home-$yesterday /var/.snapshots/home-$today | ssh [email protected] "sudo btrfs receive /volume1/NetBackup/snaps"

# if it's the first day of the week, create a weekly snapshot
if [ $(date +%u) -eq 1 ]; then
    weeknum=$(date +%U)
    sudo btrfs subvolume snapshot -r /home /var/.snapshots/home-weekly-$weeknum
    sudo btrfs send -p /var/.snapshots/home-$yesterday /var/.snapshots/home-weekly-$weeknum | ssh [email protected] "sudo btrfs receive /volume1/NetBackup/snaps"
    # delete weekly snapshots older than 4 weeks
    ssh [email protected] "sudo btrfs subvolume delete /volume1/NetBackup/snaps/home-weekly-$(date -d '4 weeks ago' +%U)"
fi
# if its the first day of the month, create a monthly snapshot
if [ $(date +%d) -eq 1 ]; then
    monthnum=$(date +%m)
    sudo btrfs subvolume snapshot -r /home /var/.snapshots/home-monthly-$monthnum
    sudo btrfs send -p /var/.snapshots/home-$yesterday /var/.snapshots/home-monthly-$monthnum | ssh [email protected] "sudo btrfs receive /volume1/NetBackup/snaps"
    # delete monthly snapshots older than 4 months
    ssh [email protected] "sudo btrfs subvolume delete /volume1/NetBackup/snaps/home-monthly-$(date -d '12 months ago' +%M)"
fi

# cleanup old snapshots locally
sudo btrfs subvolume delete /var/.snapshots/home-$twodaysago
# cleanup old daily snapshots on remote
ssh [email protected] "sudo btrfs subvolume delete /volume1/NetBackup/snaps/home-$twodaysago"

# exit
exit 0