Google DNS Extension for Plesk 18.0.26+

Requirements

Navigate to the releases tab: https://github.com/spacedog4/plesk-googledns/releases/latest
Download the extension
Add the following to your panel.ini file:
```
[ext-catalog]

extensionUpload = true
```
This makes sure that you can upload extension on the extension page.
Navigate to the Extensions page, then My Extensions. Here you can upload the extension zip.
Google DNS should now be visible in your extension list.

You need o active Cloud DNS API on Google API Console

If you are using a domain in plesk instead of the IP Address, you must add it to the authorized domains list

Go to Google Api Console
Choose your project
On the left menu, go to OAuth consent screen
Choose External
Scroll to "Authorized domains" and add your domain without any http/https or path. Ex.: my-plesk-domain.com
Press Enter
Save it

You have to create a OAuth 2.0 credential on Google API Console

Go to Google Api Console
Choose your project
On the left menu, go to Credentials
Click on "Create Credentials"
Click on "OAuth client ID"
Choose "Web Application"
Inside "Authorized redirect URIs" add your plesk domain/ip followed by /modules/googledns/index.php/index/authenticate. Ex.: https://my-plesk-domain.com/modules/googledns/index.php/index/authenticate
Save "Your Client ID" and "Your Client Secret" to set it on plesk extension later

Install the dependencies first with composer. Unlike a regular composer package the vendor folder can be found in the subdirectory src/plib. This is the folder that eventually ends up on Plesk.
This is what an extension's file structure should look like: https://docs.plesk.com/en-US/onyx/extensions-guide/plesk-extensions-basics/extension-structure.71076/