Automate your macOS backup to Backblaze B2 using Restic and launchd.

backup.sh

#!/bin/bash

PID_FILE=~/.restic_backup.pid
TIMESTAMP_FILE=~/.restic_backup_timestamp

if [ -f "$PID_FILE" ]; then
  if ps -p $(cat $PID_FILE) > /dev/null; then
    echo $(date +"%Y-%m-%d %T") "File $PID_FILE exist. Probably backup is already in progress."
    exit 1
  else
    echo $(date +"%Y-%m-%d %T") "File $PID_FILE exist but process " $(cat $PID_FILE) " not found. Removing PID file."
    rm $PID_FILE
  fi
fi

if [ -f "$TIMESTAMP_FILE" ]; then
  time_run=$(cat "$TIMESTAMP_FILE")
  current_time=$(date +"%s")

  if [ "$current_time" -lt "$time_run" ]; then
    exit 2
  fi
fi

if [[ $(networksetup -getairportnetwork en0 | grep -E "Home-Network|Work-Network") == "" ]]; then
  echo $(date +"%Y-%m-%d %T") "Unsupported network."
  exit 3
fi

if [[ $(pmset -g ps | head -1) =~ "Battery" ]]; then
  echo $(date +"%Y-%m-%d %T") "Computer is not connected to the power source."
  exit 4
fi

echo $$ > $PID_FILE
echo $(date +"%Y-%m-%d %T") "Backup start"

export B2_ACCOUNT_ID=$(security find-generic-password -s backup-restic-b2-accound-id -w)
export B2_ACCOUNT_KEY=$(security find-generic-password -s backup-restic-b2-account-key -w)
export RESTIC_REPOSITORY=$(security find-generic-password -s backup-restic-repository -w)
export RESTIC_PASSWORD_COMMAND='security find-generic-password -s backup-restic-password-repository -w'

/usr/local/bin/restic backup --verbose -o b2.connections=20 --files-from ~/backup.txt 

echo $(date +"%Y-%m-%d %T") "Backup finished"
echo $(date -v +6H +"%s") > $TIMESTAMP_FILE

rm $PID_FILE

pl.skrajewski.restic_backup.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC -//Apple Computer//DTD PLIST 1.0//EN
http://www.apple.com/DTDs/PropertyList-1.0.dtd>
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>pl.skrajewski.restic_backup</string>
  
  <key>Program</key>
  <string>/Users/szymon/scripts/backup.sh</string>

  <key>RunAtLoad</key>
  <true/>

  <key>StartInterval</key>
  <integer>300</integer>
    
  <key>WorkingDirectory</key>
  <string>/Users/szymon/</string>
  
  <key>StandardOutPath</key>
  <string>/Users/szymon/Library/Logs/pl.skrajewski.restic_backup.out.log</string>
  
  <key>StandardErrorPath</key>
  <string>/Users/szymon/Library/Logs/pl.skrajewski.restic_backup.error.log</string>
</dict>
</plist>

Note: https://szymonkrajewski.pl/macos-backup-restic/ explains reasoning of script in detail. And has following restic code to create a binary executable backup_wrapper for"MacOS Catalina: Dealing with System Integrity Protection (SIP) and new permissions"

import Foundation
import os

let task = Process()

task.launchPath = "/bin/bash"
task.arguments = ["/Users/szymon/scripts/backup.sh"]

do{
    try task.run()
}
catch{
    os_log("error")
}

task.waitUntilExit()