UDM backup to Unraid 6.9+

#!/bin/bash

## Created by Roger P, modified by knaackville
## Updated: 5/18/2022
## Created to backup my UDM backup files to Unraid NAS daily
## See https://github.com/boostchicken/udm-utilities/wiki/Backup-Your-UDM-Backup-Files-to-Another-Server for additional information.

########################
##### Prerequisite #####
########################

# Requires Unraid 6.9+ due to changes in SSH key storage.  Works with 6.10

# Unraid Steps:
## SSH Unraid and run the following commands
## # ssh-keygen (enter to all options)

# Unraid Steps:
## SSH the UDM Pro Once (Needed to save the host as known address on Unraid)
## # ssh root@<UDMIP> (successfully connect once)

## copy text from /root/.ssh/id_rsa.pub
## Add persistent SSH key to reboot of server https://github.com/boostchicken/udm-utilities/blob/master/on-boot-script/examples/udm-files/on_boot.d/15-add-root-ssh-keys.sh
## Also works with https://github.com/fire1ce/UDMP-Persistence-SSH-Keys  which is probably the preferred method now.

#####################################
##### User adjustable variables #####
#####################################

UDMServer="10.0.0.2"
toEmailAddress="[email protected]"
fromEmailAddress="[email protected]"
emailSubject="UDMPro Backup Error"
emailBody="Error backing up UDMPro configuration file for $UDMServer."
backUpPath="/mnt/user/appdata/UDMPro_backup"
backUpsToKeep=365
fixUnifi="-oHostKeyAlgorithms=+ssh-rsa -oPubkeyAcceptedAlgorithms=+ssh-rsa"

##################
##### Script #####
##################

## Check if backup directory exists, if it doesn't then create it
if [ ! -d $backUpPath ]
then
  mkdir -p $backUpPath
fi

## Get latest backup
scp $fixUnifi root@$UDMServer:/mnt/data/unifi-os/unifi/data/backup/autobackup/*.unf $backUpPath/ \
||  {
     echo To: $toEmailAddress
     echo From: $fromEmailAddress
     echo Subject: $emailSubject
     echo "$emailBody"
} | ssmtp $toEmailAddress

## Clean up old backups
if [ $(ls -t |tail -n +$(( $backUpsToKeep + 1 )) |wc -l) -gt 0 ]
then
  rm $(ls -t $backUpPath |tail -n +$(( $backUpsToKeep + 1 )))
 fi