$settings = @{
    configurationArguments = @{
        registrationUrl = "https://ne-agentservice-prod-1.azure-automation.net/accounts/xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxx"
    }
} | ConvertTo-Json -Compress

$protectedSettings = @{
    configurationArguments = @{
        registrationKey = @{
            userName = "NOT_USED"
            password = "/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=="
        }
    }
} | ConvertTo-Json -Compress

Get-AzureRmVmss -ResourceGroupName $resourceGroupName -VMScaleSetName $VmSsName |
    Add-AzureRmVmssExtension -Name "DSC" -Publisher "Microsoft.Powershell" -Type "DSC" -TypeHandlerVersion "2.24" -Setting $settings -ProtectedSetting $protectedSettings |
    Update-AzureRmVmss