The Issue with Access Tokens

Oct 13, 2025 by wbrum.org 101 views

Introduction

Are you trying to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal? You're not alone. Many developers face this challenge when trying to interact with their APIs programmatically. In this article, we'll explore the common issues and provide a step-by-step guide on how to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal.

Understanding Entra ID Easy-Auth

Entra ID Easy-Auth is a feature in Azure that provides a simple and secure way to authenticate users and protect APIs. It uses the OAuth 2.0 protocol to issue access tokens that can be used to access protected endpoints. When you enable Easy-Auth on your Azure Function App, it creates a /.auth/login endpoint that users can use to authenticate and obtain an access token.

The Problem

So, what's the problem? You've logged in interactively, obtained an access token by visiting the /.auth/me endpoint, but when you try to use it with curl to access a protected endpoint, it says you don't have permission. This is a common issue that many developers face when trying to access their APIs programmatically.

The Issue with Access Tokens

The issue lies in the way access tokens are issued and used. When you log in interactively, you obtain an access token that is specific to your user account. However, when you try to use this token to access a protected endpoint, the token is not valid because it's not associated with the user account that's making the request.

Solution: Using the Client Credentials Flow

To access your Azure Function App API protected by Entra ID Easy-Auth from the terminal, you need to use the client credentials flow. This flow is designed for server-to-server authentication, where the client (in this case, your terminal) is making a request to the API on behalf of the server.

Here's an example of how to use the client credentials flow to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal:

Step 1: Register Your Client

First, you need to register your client (your terminal) with Azure AD. This will give you a client ID and client secret that you can use to authenticate with the API.

az ad app create --display-name "My Terminal Client"

Step 2: Get Your Client ID and Client Secret

Once you've registered your client, you can get your client ID and client secret using the following command:

az ad app show --id <client_id>

Step 3: Use the Client Credentials Flow to Obtain an Access Token

Now that you have your client ID and client secret, you can use the client credentials flow to obtain an access token. You can do this using the following curl command:

curl -X POST \
  https://login.microsoftonline.com/<tenant_id>/oauth2/v2.0/token \
  -H 'Content-Type: application/x-www-form-urlencoded' \
  -d 'grant_type=client_credentials&client_id=<client_id>&client_secret=<client_secret>&scope=https://<function_app_name>.azurewebsites.net/.default'

Replace <tenant_id> with your Azure AD tenant ID, <client_id> with your client ID, <client_secret> with your client secret, and <function_app_name> with your Function App name.

Step 4: Use the Access Token to Access the Protected Endpoint

Once you have the access token, you can use it to access the protected endpoint. You can do this using the following curl command:

curl -X GET \
  https://<function_app_name>.azurewebsites.net/api/<endpoint> \
  -H 'Authorization: Bearer <access_token>'

Replace <function_app_name> with your Function App name, <endpoint> with the protected endpoint you want to access, and <access_token> with the access token you obtained in the previous step.

Conclusion

In this article, we've explored the common issues and provided a step-by-step guide on how to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal. By using the client credentials flow, you can obtain an access token that can be used to access protected endpoints. We hope this article has been helpful in resolving your issue and providing a better understanding of how to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal.

Troubleshooting Tips

Here are some troubleshooting tips to help you resolve common issues:

Make sure you've registered your client with Azure AD and obtained a client ID and client secret.
Make sure you're using the correct tenant ID, client ID, and client secret in your curl commands.
Make sure you're using the correct scope in your curl commands.
Make sure you're using the correct access token in your curl commands.
Check the Azure AD logs for any errors or issues related to your client or access token.

Additional Resources

Here are some additional resources that may be helpful:

Azure AD documentation
Entra ID Easy-Auth documentation
Azure Function App documentation
Q&A: Accessing Azure Function App API Protected by Entra ID Easy-Auth from the Terminal ====================================================================================

Frequently Asked Questions

We've received many questions from developers who are trying to access their Azure Function App API protected by Entra ID Easy-Auth from the terminal. Here are some of the most frequently asked questions and their answers:

Q: What is Entra ID Easy-Auth?

A: Entra ID Easy-Auth is a feature in Azure that provides a simple and secure way to authenticate users and protect APIs. It uses the OAuth 2.0 protocol to issue access tokens that can be used to access protected endpoints.

Q: Why do I need to use the client credentials flow?

A: The client credentials flow is designed for server-to-server authentication, where the client (in this case, your terminal) is making a request to the API on behalf of the server. This flow is necessary because the access token obtained through interactive login is not valid for server-to-server authentication.

Q: How do I register my client with Azure AD?

A: To register your client with Azure AD, you can use the following command:

az ad app create --display-name "My Terminal Client"

This will create a new client application in Azure AD.

Q: How do I get my client ID and client secret?

A: To get your client ID and client secret, you can use the following command:

az ad app show --id <client_id>

Replace <client_id> with the ID of your client application.

Q: What is the scope in the client credentials flow?

A: The scope in the client credentials flow is the set of permissions that the client application is requesting. In this case, the scope is https://<function_app_name>.azurewebsites.net/.default, where <function_app_name> is the name of your Function App.

Q: How do I use the access token to access the protected endpoint?

A: To use the access token to access the protected endpoint, you can use the following curl command:

curl -X GET \
  https://<function_app_name>.azurewebsites.net/api/<endpoint> \
  -H 'Authorization: Bearer <access_token>'

Replace <function_app_name> with the name of your Function App, <endpoint> with the protected endpoint you want to access, and <access_token> with the access token you obtained in the previous step.

Q: What are some common issues that I might encounter?

A: Some common issues that you might encounter when trying to access your Azure Function App API protected by Entra ID Easy-Auth from the terminal include:

Making sure that you've registered your client with Azure AD and obtained a client ID and client secret.
Making sure that you're using the correct tenant ID, client ID, and client secret in your curl commands.
Making sure that you're using the correct scope in your curl commands.
Making sure that you're using the correct access token in your curl commands.
Checking the Azure AD logs for any errors or issues related to your client or access token.

Troubleshooting Tips

Here are some additional troubleshooting tips to help you resolve common issues:

Make sure that you've enabled the client credentials flow in your Azure Function App.
Make sure that you've registered your client with Azure AD and obtained a client ID and client secret.
Make sure that you're using the correct tenant ID, client ID, and client secret in your curl commands.
Make sure that you're using the correct scope in your curl commands.
Make sure that you're using the correct access token in your curl commands.
Check the Azure AD logs for any errors or issues related to your client or access token.

Additional Resources

Here are some additional resources that may be helpful: