(Be forewarned: total newbie question follows):
I am currently debugging a playbook that creates two new hosts, removes two old hosts from a load balancer, then adds the two new hosts to the load balancer. We have separated many of these plays into their own playbook files and included them in a top-level play.
I want to be able to set a list of the two new hosts earlier in one play and have it persist on the machine running ansible between these nested plays, so that later on I can run a play that grabs the list of the old hosts currently in the load balancer, then use the list of the new hosts I set previously to add them to the LB, then use the list of old hosts to remove them from the LB. This is, as far as I can tell, the best way to do this, since Rackspace's rax_clb_nodes module makes changes to the load balancer from localhost.
A.) Is this the best way to achieve this?
B.) What is the best way to do this?
Facts set by set_fact are persistent between Plays.
So you can set fact for localhost and then use it later as {{ hostvars['localhost']['my_custom_fact'] }}.
Please read about Magic Variables – e.g. if you put your new hosts into separate inventory group, you can loop through this group.