JavaFX: add loading annimation in a toolbar

I want to have small loading animation on my log-in dialog, i have got toolbar with connect button and status field - ( I use simple Label to print status messages ). Sometimes connection check takes too long so need some kind of loading animation f.e: loading

what would be the best way to achieve this? Problem i'm having at the moment is that can't make image to go inactive, i only need the image to be active while app steps into my connection checking and validation methods...