when you pass in a func to an apply method, is it executed async?

yes, it's executed when the outputs resolve

can this behaviour be changed? Reason I ask is I call a console app from a method I invoke in the apply. I am getting errors about conflicting values (the values are being persisted in octopus deploy). So I need the method call to be blocking.

no it can't be changed, but you can add your own logic inside the apply to block

hmm some way to block. I am not quite sure the best way. Either i get all the values first and then invoke the callback, or I call the callback and wait for it to finish before it is executed again.