Check the access token format

Oct 13, 2025 by talynt.org 2 views

Introduction

When working with Azure Function Apps, securing them with Entra ID Easy Auth is a great way to manage access to your APIs. However, when trying to access these APIs from the terminal using tools like curl, you may encounter issues. In this article, we will explore how to access a 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 allows you to easily add authentication to your Function Apps. It provides a simple way to manage access to your APIs by authenticating users and issuing access tokens. When a user logs in to your Function App, Easy Auth issues an access token that can be used to access protected endpoints.

Logging in Interactively

To access your Function App API from the terminal, you first need to log in interactively. You can do this by navigating to the /login endpoint of your Function App. This will prompt you to enter your credentials, and once you log in, you will be redirected to the /auth/me endpoint to retrieve your access token.

curl -X GET \
  https://your-function-app.azurewebsites.net/.auth/login \
  -H 'Content-Type: application/x-www-form-urlencoded'

After logging in, you can retrieve your access token by navigating to the /auth/me endpoint.

curl -X GET \
  https://your-function-app.azurewebsites.net/.auth/me \
  -H 'Content-Type: application/x-www-form-urlencoded'

Using the Access Token with Curl

Once you have retrieved your access token, you can use it to access protected endpoints. However, when trying to use the access token with curl, you may encounter issues. The error message "You do not have permission to access this resource" is often displayed.

curl -X GET \
  https://your-function-app.azurewebsites.net/api/protected-endpoint \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN'

Resolving the Permission Issue

The permission issue is often caused by the fact that the access token is not being sent correctly in the Authorization header. To resolve this issue, you need to ensure that the access token is being sent correctly in the Authorization header.

Here are a few things you can try:

Check the access token format: Make sure that the access token is in the correct format. It should be a JSON Web Token (JWT) that contains the user's identity information.
Check the Authorization header: Make sure that the Authorization header is being sent correctly. It should contain the string "Bearer" followed by the access token.
Check the endpoint URL: Make sure that the endpoint URL is correct. It should match the URL of the protected endpoint in your Function App.

Using the Azure CLI to Access the API

Another way to access your Function App API from the terminal is by using the Azure CLI. The Azure CLI provides a set of commands that allow you to interact with Azure resources, including Function Apps.

Here is an example of how you can use the Azure CLI to access your Function App API:

az login
az account get-access-token --resource https://your-function-app.azurewebsites.net/.default
curl -X GET \
  https://your-function-app.azurewebsites.net/api/protected-endpoint \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN'

Conclusion

In this article, we explored how to access a Function App API protected by Entra ID Easy Auth from the terminal. We discussed the importance of logging in interactively and retrieving the access token, and we provided examples of how to use the access token with curl and the Azure CLI. By following the steps outlined in this article, you should be able to access your Function App API from the terminal without encountering permission issues.

Troubleshooting Tips

Here are a few troubleshooting tips to help you resolve permission issues when accessing your Function App API from the terminal:

Check the access token format: Make sure that the access token is in the correct format. It should be a JSON Web Token (JWT) that contains the user's identity information.
Check the Authorization header: Make sure that the Authorization header is being sent correctly. It should contain the string "Bearer" followed by the access token.
Check the endpoint URL: Make sure that the endpoint URL is correct. It should match the URL of the protected endpoint in your Function App.
Check the Azure CLI version: Make sure that you are using the latest version of the Azure CLI. You can check the version by running the command az --version.
Check the Azure subscription: Make sure that you are using the correct Azure subscription. You can check the subscription by running the command az account show.

Additional Resources

Here are a few additional resources that you can use to learn more about accessing Function App APIs from the terminal:

Azure Function Apps documentation: The official documentation for Azure Function Apps provides a wealth of information on how to secure your APIs with Entra ID Easy Auth.
Azure CLI documentation: The official documentation for the Azure CLI provides a wealth of information on how to use the Azure CLI to interact with Azure resources.
Stack Overflow: Stack Overflow is a great resource for finding answers to common questions about Azure and Azure Function Apps.

Conclusion

Q: What is Entra ID Easy Auth?

A: Entra ID Easy Auth is a feature in Azure that allows you to easily add authentication to your Function Apps. It provides a simple way to manage access to your APIs by authenticating users and issuing access tokens.

Q: How do I log in interactively to access my Function App API?

A: To log in interactively, navigate to the /login endpoint of your Function App. This will prompt you to enter your credentials, and once you log in, you will be redirected to the /auth/me endpoint to retrieve your access token.

curl -X GET \
  https://your-function-app.azurewebsites.net/.auth/login \
  -H 'Content-Type: application/x-www-form-urlencoded'

Q: How do I retrieve my access token?

A: After logging in, you can retrieve your access token by navigating to the /auth/me endpoint.

curl -X GET \
  https://your-function-app.azurewebsites.net/.auth/me \
  -H 'Content-Type: application/x-www-form-urlencoded'

Q: How do I use the access token with `curl`?

A: Once you have retrieved your access token, you can use it to access protected endpoints. However, when trying to use the access token with curl, you may encounter issues. The error message "You do not have permission to access this resource" is often displayed.

curl -X GET \
  https://your-function-app.azurewebsites.net/api/protected-endpoint \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN'

Q: What are some common issues that can cause permission problems when accessing my Function App API?

A: Some common issues that can cause permission problems when accessing your Function App API include:

Incorrect access token format: Make sure that the access token is in the correct format. It should be a JSON Web Token (JWT) that contains the user's identity information.
Incorrect Authorization header: Make sure that the Authorization header is being sent correctly. It should contain the string "Bearer" followed by the access token.
Incorrect endpoint URL: Make sure that the endpoint URL is correct. It should match the URL of the protected endpoint in your Function App.

Q: How can I troubleshoot permission issues when accessing my Function App API?

A: Here are a few troubleshooting tips to help you resolve permission issues when accessing your Function App API:

Check the access token format: Make sure that the access token is in the correct format. It should be a JSON Web Token (JWT) that contains the user's identity information.
Check the Authorization header: Make sure that the Authorization header is being sent correctly. It should contain the string "Bearer" followed by the access token.
Check the endpoint URL: Make sure that the endpoint URL is correct. It should match the URL of the protected endpoint in your Function App.
Check the Azure CLI version: Make sure that you are using the latest version of the Azure CLI. You can check the version by running the command az --version.
Check the Azure subscription: Make sure that you are using the correct Azure subscription. You can check the subscription by running the command az account show.

Q: Can I use the Azure CLI to access my Function App API?

A: Yes, you can use the Azure CLI to access your Function App API. The Azure CLI provides a set of commands that allow you to interact with Azure resources, including Function Apps.

Here is an example of how you can use the Azure CLI to access your Function App API:

az login
az account get-access-token --resource https://your-function-app.azurewebsites.net/.default
curl -X GET \
  https://your-function-app.azurewebsites.net/api/protected-endpoint \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN'

Q: Where can I find more information about accessing Function App APIs from the terminal?

A: Here are a few additional resources that you can use to learn more about accessing Function App APIs from the terminal:

Azure Function Apps documentation: The official documentation for Azure Function Apps provides a wealth of information on how to secure your APIs with Entra ID Easy Auth.
Azure CLI documentation: The official documentation for the Azure CLI provides a wealth of information on how to use the Azure CLI to interact with Azure resources.
Stack Overflow: Stack Overflow is a great resource for finding answers to common questions about Azure and Azure Function Apps.

Q: What are some best practices for securing my Function App API?

A: Here are a few best practices for securing your Function App API:

Use Entra ID Easy Auth: Entra ID Easy Auth is a feature in Azure that allows you to easily add authentication to your Function Apps. It provides a simple way to manage access to your APIs by authenticating users and issuing access tokens.
Use HTTPS: Make sure that your Function App API is using HTTPS to encrypt data in transit.
Use Azure Active Directory: Azure Active Directory is a cloud-based identity and access management solution that provides a secure way to manage access to your Function App API.
Use role-based access control: Role-based access control is a security feature that allows you to manage access to your Function App API based on user roles.

Q: How can I stay up-to-date with the latest information about Azure and Azure Function Apps?

A: Here are a few ways to stay up-to-date with the latest information about Azure and Azure Function Apps:

Azure blog: The Azure blog provides a wealth of information about Azure and Azure Function Apps.
Azure documentation: The Azure documentation provides a wealth of information about Azure and Azure Function Apps.
Azure community: The Azure community is a great resource for finding answers to common questions about Azure and Azure Function Apps.
Azure events: Azure events are a great way to learn about the latest features and updates to Azure and Azure Function Apps.