Mikrotik Dynamic DNS (DDNS) update with Google Cloud (GCP) function on Google Cloud DNS

README.md

1. Generate a service account with DNS admin rights and download the json.
2. Generate a service for unauthenticated calls
3. Create a cloud function and upload the index.js, package.json and service acount json
   • 128MB RAM is enough
   • HTTP trigger should be set
   • Unauthenticated call should be set
   • 2. service account should be selected
   • Add the following environment variables:
     • PROJECT_NAME: name of the project, where the DNS is defined
     • RECORD_NAME: name of the DNS record, what should be updated. A . is required in the end, like: home.example.com.
     • SECRET: a secret string that should be passed during api call in query parameter
     • GOOGLE_APPLICATION_CREDENTIALS: name of your 1. service account json file, like ./project-123.json
4. Set a sceduler in mikrotik router with the following command: /tool fetch url="https://europe-west3-projectid.cloudfunctions.net/functionname\?secret=hereisyoursecret" keep-result=no

index.js

const { DNS } = require('@google-cloud/dns');
const dns = new DNS();

const { PROJECT_NAME, RECORD_NAME, SECRET } = process.env;

exports.app = async (req, res) => {
	const ip = req.headers['x-forwarded-for'];

	if ([PROJECT_NAME, RECORD_NAME, SECRET].some(environmentVariable => typeof environmentVariable === 'undefined')) {
		return res.end('Incorrectly configured environment');
	}

	if (req.query.secret !== SECRET) {
		return res.end('Incorrect secret');
	}

	const zone = dns.zone(PROJECT_NAME);
	const [record] = await zone.getRecords({ name: RECORD_NAME, type: 'A' });
	const change = {};
	if (record) {
		change.delete = record;
	}

	change.add = zone.record('A', {
		name: RECORD_NAME,
		data: ip,
		ttl: 300
	});

	await zone.createChange(change);
	return res.end(`Your ip is ${JSON.stringify(ip)} and it's been set`);
  };
  

package.json

{
  "name": "home-dns",
  "version": "0.0.1",
  "dependencies": {
    "@google-cloud/dns": "^1.2.1"
  }
}

serviceaccount.json

{
  "type": "service_account",
  "project_id": "project",
  "private_key_id": "abc",
  "private_key": "-----BEGIN PRIVATE KEY-----\ndef\n-----END PRIVATE KEY-----\n",
  "client_email": "xxx",
  "client_id": "123",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://oauth2.googleapis.com/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/..."
}