Yii on Azure with Remote Access

I have a Yii app running on Azure with an Azure SQL db. This all works beautifully.

Now to access the app, one has to first authenticate through Azure, and then authenticate through the Yii app login. Once again, this work just fine.

I’ve been asked if it would be possible to allow an external app to transfer (full crud permisssions) information to this Yii app through an API.

Correct me if I’m wrong, never looked into this before, is this where a REST API would come into play?
How does a REST API authenticate to have access (both Azure and Yii)?

Can anyone offer a brief overview of the direction I’d need to take/explore?

Thank you.

is this where a REST API would come into play?

I would think so! Follow link below:

How does a REST API authenticate (Yii)

How does a REST API authenticate (Azure)

For this you may have to refer to Azure documentation. This auth is just to get to the Yii URL and I would assume this would have nothing to do with Yii itself.

allow an external app to transfer (full crud permisssions) information to this Yii app

This is not different from passing permissions in the Yii front-end app. The article link I sent earlier suggests you create a separate app just for Web services. I would assume you specify what permissions are required just as how you would for a regular app, expect the exchanges will likely be JSON.