Function app - identity provider authentication

I'm trying to add authentication to my Azure Function App before allowing requests to be processed.

To avoid handling tokenization manually, I attempted to configure the Identity Provider for my Function App.

What I've Done So Far: Created an App Registration with the following configurations:

Authentication page:

API Permissions:

Expose an API

Identity Provider

The Issue: When I try to test or run my function, I receive a 401 Unauthorized error. I expected the Identity Provider to handle authentication automatically. However, when I click on default domain, it does not request authorization. Instead, a new window opens with the following screens:

Additional Observations:

If I manually navigate to https://func-myfunc-01.azurewebsites.net/.auth/login/aad/callback, authentication works, and I get authorized successfully.

My Goal:

I want users to be prompted for authentication before accessing the Function URL. Once authenticated, they should be able to execute the function.

What am I doing wrong? Any guidance would be greatly appreciated.

Thanks!

Authentication and authorization are different from each other. Adding Identity provider for our Azure function instance provides us a simple way to secure function endpoints.

Authentication requires to sign-in ahead then visit secured resource, so that we need to set a redirection(http 302 performs URL redirection), while authorization always requires a valid access token in request header and will return 401 error to indicate there's no token or token is invalid, or return 403 error code to indicate token in valid but has insufficient access permission.

OP confirmed that choose 302 redirect instead of 401 when adding the identity provider for Azure function can resolve his issue.