[FEATURE REQ] Support object ID for ManagedIdentityCredential in AzureComponentFactory

[scottaddie]

Library name

Microsoft.Extensions.Azure

Please describe the feature.

The Azure Identity library's ManagedIdentityCredential is being enhanced to support object ID for user-assigned managed identity. See #45605. Object ID is an alternative to using client ID or resource ID. With regards to ManagedIdentityCredential, we should have feature parity between Azure.Identity and Microsoft.Extensions.Azure. It would involve updating this code:

azure-sdk-for-net/sdk/extensions/Microsoft.Extensions.Azure/src/Internal/ClientFactory.cs

Lines 115 to 128 in 91dc3f1

	if (string.Equals(credentialType, "managedidentity", StringComparison.OrdinalIgnoreCase))
	{
	if (!string.IsNullOrWhiteSpace(clientId) && !string.IsNullOrWhiteSpace(resourceId))
	{
	throw new ArgumentException("Cannot specify both 'clientId' and 'managedIdentityResourceId'");
	}
	if (!string.IsNullOrWhiteSpace(resourceId))
	{
	return new ManagedIdentityCredential(new ResourceIdentifier(resourceId));
	}
	return new ManagedIdentityCredential(clientId);
	}

From a customer's perspective, they should be able to provide configuration like the following:

{
    "credential": "managedidentity",
    "managedIdentityObjectId":  "<managedIdentityObjectId>"
}

Since we don't support object ID via DefaultAzureCredential, the following code flow is unaffected:

azure-sdk-for-net/sdk/extensions/Microsoft.Extensions.Azure/src/Internal/ClientFactory.cs

Lines 218 to 249 in 91dc3f1

	if (additionallyAllowedTenantsList != null
	|| !string.IsNullOrWhiteSpace(tenantId)
	|| !string.IsNullOrWhiteSpace(clientId)
	|| !string.IsNullOrWhiteSpace(resourceId))
	{
	var options = new DefaultAzureCredentialOptions();
	if (additionallyAllowedTenantsList != null)
	{
	foreach (string tenant in additionallyAllowedTenantsList)
	{
	options.AdditionallyAllowedTenants.Add(tenant);
	}
	}
	if (!string.IsNullOrWhiteSpace(tenantId))
	{
	options.TenantId = tenantId;
	}
	if (!string.IsNullOrWhiteSpace(clientId))
	{
	options.ManagedIdentityClientId = clientId;
	}
	// validation that both clientId and ResourceId are not set happens in Azure.Identity
	if (!string.IsNullOrWhiteSpace(resourceId))
	{
	options.ManagedIdentityResourceId = new ResourceIdentifier(resourceId);
	}
	return new DefaultAzureCredential(options);
	}

[christothes]

This change can be made after we ship the October release of Azure.Identity.

[scottaddie]

That sounds like a fine plan to me