OPNSense: Scripts to run as a cron job to enable or disable wireguard based on the CARP status

README.md

Installation

• Install checkWireguard as /usr/local/opnsense/scripts/OPNsense/Wireguard/checkWireguard
• Install actions_wireguardCarp.conf as /usr/local/opnsense/service/conf/actions.d/actions_wireguardCarp.conf
• run service configd restart
• In the OPNSense UI - add a CRON job in System -> Settings -> Cron to call the script

actions_wireguardCarp.conf

[check]
command: /usr/local/opnsense/scripts/OPNsense/Wireguard/checkWireguard
parameters:
type:script
message: Updating Wireguard State
description: Enable or Disable Wireguard state from CARP state

checkWireguard

#!/usr/local/bin/php
<?php

/*
 * Copyright (C) 2022 GradeCam
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

// Some of the ideas and methods of this come from this script:
//  https://gist.github.com/jprenken/18ca7bf14ddae547ae0fdf6f56d72573

require_once("config.inc");
require_once("interfaces.inc");
require_once("util.inc");

$cmd = "/sbin/ifconfig -m -v | grep 'carp:' | awk '{print $2}'";

exec($cmd, $ifconfig_data, $ret);

$masterCount = 0;
$backupCount = 0;

// Loop over $ifconfig_data and count how many are "MASTER" and how many "BACKUP"
foreach ($ifconfig_data as $line) {
  if (strpos($line, 'MASTER') !== false) {
    $masterCount++;
  } else if (strpos($line, 'BACKUP') !== false) {
    $backupCount++;
  }
}

if ($masterCount > $backupCount) {
  // The current node is MASTER
  echo "CARP MASTER detected\n";

# Checking `isset` avoids a race condition during startup when the
  # WireGuard config stanza seems like it's not yet loaded. Without it, this
  # can create an extra, empty, invalid stanza that breaks WireGuard.
  if (isset($config['OPNsense']['wireguard']['general']['enabled'])) {
    $config['OPNsense']['wireguard']['general']['enabled'] = '1';
  }
  configd_run('wireguard start');
  write_config("Enable WireGuard due to CARP event '$type'", false);
} else {
  echo "CARP BACKUP detected\n";

  configd_run('wireguard stop');
  if (isset($config['OPNsense']['wireguard']['general']['enabled'])) {
    $config['OPNsense']['wireguard']['general']['enabled'] = '0';
  }
  write_config("Disable WireGuard due to CARP event '$type'", false);
}