[azclient] Refactor AuthProvider multi-tenant token credential

[zarvd]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Refactor the AuthProvider to remove the MultiTenantCredential, as the ComputeCredential would work the same and provide the client options while using the auxiliary token provider.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Hi @zarvd. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[zarvd]

@MartinForReal Kindly note that I have also add the missing option here. please take a look, thanks.

[MartinForReal]

Is there any reference to this field?

[zarvd]

Will be used in L418 in https://github.com/zarvd/cloud-provider-azure/blob/b24b7a4a34c24199494a18b1859db89584558594/pkg/provider/azure.go#L401-L427.

Compared to the existing one

cloud-provider-azure/pkg/provider/azure.go

Lines 405 to 453 in a2e9ea1

	if az.ComputeClientFactory == nil {
	var cred azcore.TokenCredential
	if az.AuthProvider.IsMultiTenantModeEnabled() {
	// It uses Service Principal as the multi-tenant credential.
	// TODO: refactor `IsMultiTenantModeEnabled` to make it more clear.
	multiTenantCred := az.AuthProvider.GetMultiTenantIdentity()
	networkTenantCred := az.AuthProvider.GetNetworkAzIdentity()
	az.NetworkClientFactory, err = azclient.NewClientFactory(&azclient.ClientFactoryConfig{
	SubscriptionID: az.NetworkResourceSubscriptionID,
	}, &az.ARMClientConfig, clientOps.Cloud, networkTenantCred)
	if err != nil {
	return err
	}
	cred = multiTenantCred
	} else {
	cred = az.AuthProvider.GetAzIdentity()
	}
	var opts []func(option *arm.ClientOptions)
	if az.AzureAuthConfig.AuxiliaryTokenProvider != nil && az.AzureAuthConfig.UseManagedIdentityExtension {
	klog.InfoS("Using auxiliary token provider for ARM network credential")
	// Multi-tenant mode with auxiliary token provider.
	// It uses Managed Identity as the primary credential and auxiliary token provider as the auxiliary credential.
	opts = append(opts, func(option *arm.ClientOptions) {
	option.PerRetryPolicies = append(option.PerRetryPolicies, armauth.NewAuxiliaryAuthPolicy(
	[]azcore.TokenCredential{az.AuthProvider.GetNetworkAzIdentity()},
	az.AuthProvider.DefaultTokenScope(),
	))
	})
	az.NetworkClientFactory, err = azclient.NewClientFactory(&azclient.ClientFactoryConfig{
	SubscriptionID: az.NetworkResourceSubscriptionID,
	}, &az.ARMClientConfig, clientOps.Cloud, az.AuthProvider.GetNetworkAzIdentity())
	if err != nil {
	return err
	}
	}
	az.ComputeClientFactory, err = azclient.NewClientFactory(&azclient.ClientFactoryConfig{
	SubscriptionID: az.SubscriptionID,
	}, &az.ARMClientConfig, clientOps.Cloud, cred, opts...)
	if err != nil {
	return err
	}
	if az.NetworkClientFactory == nil {
	az.NetworkClientFactory = az.ComputeClientFactory
	}
	}

[zarvd]

Please take a closer look; it's moved to the else branch in L213.

[MartinForReal]

/ok-to-test