[BUG]Azure.Identity.CredentialUnavailableException exception at function startup for QueueTrigger about azure-sdk-for-net

[jsquire]

Hi @Gamecock. Thank you for reaching out and we regret that you're experiencing difficulties. This is normal and expected behavior, as the Functions infrastructure configures a DefaultAzureCredential instance as part of its dependency injection. As a chained credential, DefaultAzureCredential will try several different credential types and use the first that is available on the host environment. In this case, the attempt to use a managed identity fails, as your local host does not have an MI endpoint. More information is available in the DefaultAzureCredential documentation.

If desired, you can configure the DefaultAzureCredentialOptions used to remove undesired credentials from the chain or switch to a more specific credential. To do so, you write a Function startup class to participate in the DI configuration. (see: Use dependency injection in .NET Azure Functions)

In your DI registration, you would use the Azure extensions to override the default credential used with one configured as you'd like. For example, configuring the options for DefaultAzureCredential would look something like:

using Azure.Identity;
using Microsoft.Extensions.Azure;
using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection;

[assembly: FunctionsStartup(typeof(MyNamespace.Startup))]

namespace MyNamespace;

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
        builder.Services.AddAzureClients(azureBuilder => 
        {
            var options = new DefaultAzureCredentialOptions
            {
                ExcludeManagedIdentityCredential = true
            };

            // Configure a new credential to be used by default
            // for all clients that require TokenCredential.

            azureBuilder.UseCredential(new DefaultAzureCredential(options));
        });
    }
}

This would also allow you to create a different credential type, such as a chained credential that includes only VS and VSCode for local development scenarios.

More information and examples for configuring Azure clients in DI can be found in: Dependency injection with the Azure SDK for .NET.

[github-actions]

Hi @Gamecock. Thank you for opening this issue and giving us the opportunity to assist. We believe that this has been addressed. If you feel that further discussion is needed, please add a comment with the text "/unresolve" to remove the "issue-addressed" label and continue the conversation.

[github-actions]

Hi @Gamecock, since you haven’t asked that we /unresolve the issue, we’ll close this out. If you believe further discussion is needed, please add a comment /unresolve to reopen the issue.

[Gamecock]

/unresolve

[Gamecock]

I updated the builder as you suggested, but same error. Feels wrong that DI should throw an exception when it's working correctly. This is what the start of my DI Configuration looks like now.

`    .ConfigureServices(s => 
        {
        //  https://github.com/Azure/azure-sdk-for-net/issues/42161
            s.AddAzureClients(azureBuilder =>
            {
                 var options = new DefaultAzureCredentialOptions
            {
                ExcludeManagedIdentityCredential = true
            };
    
        // Configure a new credential to be used by default
        // for all clients that require TokenCredential.

        azureBuilder.UseCredential(new DefaultAzureCredential(options));
        });`

[jsquire]

The error that you're seeing is from the Azure.Identity library and is how its credentials operate. The DI extensions have no influence nor control over their behavior. Opting out of managed identity will stop the managed identity credential from being used, but DefaultAzureCredential is still a chained type and will continue to probe other credentials until an available source is found. If you want to prevent errors from appearing entirely, you'd need to use the specific credential for the auth type that you'd like to use or configure logging to opt-out of gathering the Azure Identity source.

If you'd like to provide a slice of the Azure Identity logs that are being captured, then we'd be happy to take a look and advise which credentials are returning the specific errors that you are now seeing without MI enabled.

[github-actions]

Hi @Gamecock. Thank you for opening this issue and giving us the opportunity to assist. To help our team better understand your issue and the details of your scenario please provide a response to the question asked above or the information requested above. This will help us more accurately address your issue.