Sync Proxmox's native backups to rsync.net

Proxmox has an in-built backup system which is different from Proxmox Backup Server (which I now use).

Once setup, I used a script similar to the following to sync the backup files to rsync.net:

#!/bin/bash

if [[ $1 == "backup-end" && "${DUMPDIR}" ]]; then
	SOURCE_FILE=${TARGET}
	TARGET_FILE="proxmox-server-backup/$VMTYPE-$3"
	
	echo "Will now upload to rsync-net: $SOURCE_FILE to $TARGET_FILE"
	ssh de1682@de1682.rsync.net rm $TARGET_FILE
	rsync -azPH $SOURCE_FILE "de1682@de1682.rsync.net:$TARGET_FILE"
	curl -m 10 --retry 5 https://hc-ping.com/ktUIh79JnI51jskrZE6UgA/$3/$?
fi

Other resources:

Example hook script here: /usr/share/doc/pve-manager/examples/vzdump-hook-script.pl
I had to setup the hook script here: /etc/vzdump.conf.