Script properties are the best-practice way to manage secrets that apply to a Google Apps Script project, including custom connectors in Google Data Studio.
- Open the script in Google Apps Script
- Go to File > Project Properties
- Note: As of 2021-07-31, this is only accessible in the classic editor. If you have switched to the new editor, you will have to switch back in order to edit the script properties.
- Go to the “Script properties” tab
- Add a row for each property your script uses, setting the property name and value