When I first set up a .NET application on my Mac and encountered the error DefaultAzureCredential failed to retrieve a token from the included credentials, it was one of those moments where I thought I might be missing a configuration or overlooking a setting. However, this error is actually fairly common among developers when integrating Azure services into .NET apps. If you’ve hit this wall too, then this post is for you. I’ll walk you through what this error means, why it occurs, and several solutions to troubleshoot it effectively on macOS.
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Understanding the “DefaultAzureCredential Failed to Retrieve a Token” Error
When developing applications that connect to Azure resources, especially in .NET, the SDK provides the DefaultAzureCredential class to simplify authentication. This class is designed to work seamlessly in production environments, such as virtual machines or Azure Functions, where it automatically picks up the service’s identity. But on a local machine, it tries a few different methods in order: Azure CLI credentials, environment variables, and a few other fallback options.
On a new setup, especially on macOS, if you haven’t logged in to Azure CLI, the application won’t be able to retrieve a token. This causes the DefaultAzureCredential to fail, as it’s unable to authenticate using any of the available methods. Fortunately, solving this is usually straightforward, and I’ll guide you through the steps that worked for me.
Step 1: Install and Configure Azure CLI on macOS
The DefaultAzureCredential class often relies on the Azure CLI to provide credentials, so it’s essential to have the Azure CLI installed on your Mac. If you haven’t installed it yet, here’s how:
- First, make sure Homebrew is up to date. Open your terminal and run:
brew update- Next, install the Azure CLI using Homebrew:
brew install azure-cli- Once installed, you’ll need to log in to your Azure account. Run:
az loginThis command will open your browser and prompt you to sign in. Once you’re logged in, the Azure CLI will cache your credentials locally, allowing the DefaultAzureCredential to retrieve them when needed.
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$7.99 (as of December 21, 2024 19:39 GMT +00:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)Step 2: Check Azure Identity Permissions
With the Azure CLI authenticated, the next step is to ensure that your Azure identity has the appropriate permissions for the resources you’re trying to access. For example, if your application needs to read data from an Azure Key Vault or access a storage account, your identity must have the right permissions set.
If you’re developing locally with an account that has limited access to these resources, you may need to update permissions in the Azure portal. Head over to the relevant resource (like your Key Vault or storage account) and verify that your Azure CLI user is assigned an appropriate role, such as Contributor or Reader. If not, add it under “Access Control (IAM)” and select the relevant role.
Step 3: Configuring Environment Variables for Credentials
If Azure CLI-based authentication isn’t an option for you, another approach is to use environment variables to set up authentication manually. Here’s how you can configure this:
- First, collect the following credentials from your Azure portal:
- Client ID: This is your application’s ID.
- Tenant ID: This is associated with your Azure Active Directory (AAD) tenant.
- Client Secret: This is the password generated for the app registration.
- Once you have these, you can set them as environment variables in your terminal session:
export AZURE_CLIENT_ID="<your-client-id>"
export AZURE_TENANT_ID="<your-tenant-id>"
export AZURE_CLIENT_SECRET="<your-client-secret>"- For a more permanent setup, you can add these lines to your shell profile file, like
.zshrcor.bash_profile, depending on the shell you’re using. This will ensure that the environment variables are set whenever you start a new terminal session. - Now, restart your terminal or source your profile:
source ~/.zshrcWith these variables set, the DefaultAzureCredential class can pick up the credentials from your environment variables and authenticate your application locally.
Step 4: Avoiding Managed Identity on Local Machines
In Azure environments, the DefaultAzureCredential class can use Managed Identity—a powerful feature for service-to-service authentication. However, this doesn’t work on local machines, and when the credential chain includes Managed Identity, it can sometimes trigger the token retrieval error.
To avoid this, make sure that you’re not inadvertently setting up your app to rely on Managed Identity when running locally. Instead, ensure you’re using either the Azure CLI or environment variables, as mentioned in previous steps.
Step 5: Testing and Debugging with Specific Credential Types
While DefaultAzureCredential provides a convenient multi-step approach, it can sometimes be helpful to explicitly specify which credential type you’d like to use for testing purposes. If you want to narrow down the root cause, try replacing DefaultAzureCredential with a specific credential type in your code.
Here’s how:
using Azure.Identity;
// For CLI-based authentication
var credential = new AzureCliCredential();
// Or, for environment variable-based authentication
var credential = new EnvironmentCredential();Using a specific credential type can help identify whether one of the fallback methods in DefaultAzureCredential is causing the problem. This approach is particularly useful if you need to debug further and avoid confusion with multiple credential sources.
Step 6: Enabling Detailed Logging for Diagnostic Purposes
If you’re still running into issues, enabling logging can provide valuable insights into what’s happening behind the scenes. Here’s how to enable detailed logging in your application:
using Azure.Core.Diagnostics;
using Azure.Identity;
var credential = new DefaultAzureCredential();
using (AzureEventSourceListener listener = new AzureEventSourceListener(
(eventArgs, text) => Console.WriteLine(text),
System.Diagnostics.Tracing.EventLevel.Verbose))
{
// Call the method that uses the credential here
}This logging setup will display detailed messages from the Azure SDK in your console, helping you pinpoint where the credential chain might be failing. Be sure to test again after enabling logging to see if any specific errors or warnings appear.
Wrapping Up
The “DefaultAzureCredential failed to retrieve a token” error can be frustrating, but in most cases, it’s a sign of missing or misconfigured credentials. By installing and logging into the Azure CLI, setting the right permissions, configuring environment variables, and using specific credential types, you can usually resolve this error without too much trouble.
And remember, macOS is often a bit more particular about permissions and configurations, so don’t be surprised if it takes a bit of trial and error. With these steps, however, you should have the tools to get your .NET app up and running locally, authenticated and ready to interact with your Azure resources smoothly.
