macOS: Simple Time Machine Backup Checker conformed to nagios/sensu/mackerel plugin format.

check_tmbackup.rb

#!/usr/bin/env ruby
#
# you need add 'full disk access' privilege to /opt/homebrew/opt/mackerel-agent/bin/mackerel-agent.

class Main
  require 'timeout'

  CRITERIA = 3

  def run
    if time = latest_time
      if time > Time.now - (CRITERIA * 60 ** 2).to_i
        ok 'latest backup time is %s' % time
      else
        critical 'latest backup time is too old!: %s' % time
      end
    else
      critical 'failed to get latest backup date!'
    end
  end

  private

  def ok(msg)
    puts 'OK: %s' % msg
    exit 0
  end

  def critical(msg)
    puts 'CRITICAL: %s' % msg
    exit 2
  end

  def latest_time
    if /\A(\d{4})-(\d{2})-(\d{2})-(\d{6})\n\z/ =~ status_line
      year, month, day = $1, $2, $3
      hour, min, sec   = $4.unpack('A2 A2 A2')

      Time.local(sec, min, hour, day, month, year, nil, nil, false, nil)
    end
  end

  def status_line
    Timeout.timeout(15) do
      `/usr/bin/tmutil latestbackup -t`
    end
  rescue Timeout::Error
    nil
  end
end

Main.new.run