Feedback for the Issue: Unauthorized Access to Azure Function App Using Postman with Google OAuth2

[Sampath280]

Type of issue

Missing information

Feedback

Issue Summary:
The user encounters an "Unauthorized" error when attempting to access an Azure Function App secured with Google as the identity provider. Using tokens obtained via Postman, both access_token and id_token fail to authenticate the request.

Analysis and Suggestions:
Distinguishing Between access_token and id_token:

access_token: Used to authenticate API requests. This is the correct token to use when invoking the Azure Function App.
id_token: Provides user identity details and is not valid for API access. It’s primarily for client-side validation and should not be used in the Authorization header.
Validation of Access Token:

Azure Function Apps with authentication enabled typically verify the access_token against the identity provider (Google in this case).
Ensure that the token audience (aud) in the access_token matches the Function App's expected audience (likely the Function App's URL).
Steps to Resolve:

Verify Azure Function App Configuration:
In Azure Portal, under the Authentication section of the Function App, ensure that:
Identity Provider: Google is correctly configured.
Token Validation: Ensure proper settings for acceptable audiences.
Validate the Access Token:
Decode the access_token using a tool like JWT.io.
Check the aud claim and ensure it matches the Function App's URL or the client ID configured in Azure.
Correct Postman Request:
Ensure the token from Google includes the necessary scopes (openid, email, profile) and matches the expected audience.
Use the access_token in the Bearer token field of the Authorization tab in Postman.
Troubleshooting Steps:

Check Azure Function Logs:
Navigate to Monitoring > Logs in Azure Portal for the Function App.
Look for detailed error messages about the failed authentication.
Review Google OAuth Configuration:
Confirm the redirect URIs and authorized origins match what’s specified in the Azure Function App and Postman.
Use Diagnostic Tools:

Enable Application Insights in the Function App to capture authentication and request details.
Suggestions for Documentation Improvement:
Clarify Token Usage in Examples:
Differentiate access_token and id_token in Azure documentation with examples for each use case.
Add Debugging Steps:
Include common scenarios for troubleshooting Azure Function App authentication errors when using third-party identity providers.
Improve Integration Guidance for Google OAuth:
Provide detailed steps for validating Google access_token audience claims and mapping them to Azure Function App

Page URL

https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/app-service/configure-authentication-provider-google.md

Content source URL

https://learn.microsoft.com/en-us/azure/app-service/configure-authentication-provider-google

Author

@Rageking8

Document Id

2b2f9abf-9120-4aac-ac5b-4a268d9b6e2b

title: Configure Google authentication
ms.topic: article
ms.date: 03/29/2021
ms.custom: fasttrack-edit, AppServiceIdentity
author: cephalin
ms.author: cephalin

[TPavanBalaji]

@Sampath280
Thanks for your feedback! We will investigate and update as appropriate.

[PesalaPavan]

@Sampath280
Thanks for your feedback! I've assigned this issue to the author who will investigate and update as appropriate.