Any user facing restful data source connection API to create a data source connection ?

Hi YangyangGao ,

Base on your description, it seems like you are trying to create a connection to Power BI via REST API without hardcoding credentials and access an external data source through Fabric Notebook. 

1. Create a Data Source Connection

OAuth 2.0 client credentials flow on the Microsoft identity platform - Microsoft identity platform | Microsoft Learn

How to create a REST connection - Microsoft Fabric | Microsoft Learn

2. Retrieve Credentials in Your Notebook 

powerbi - Power BI and Azure Key vault - Stack Overflow

Bring your own encryption keys for Power BI - Power BI | Microsoft Learn

3. Access External Data Source via Fabric Notebook

Load data into your lakehouse with a notebook - Microsoft Fabric | Microsoft Learn

Best Regards