[ClusterLabs] Preferred node for a service (not constrained)

[Petr Bena]

Hello,

Is there a way to setup a preferred node for a service? I know how to
create constrain that will make it possible to run a service ONLY on
certain node, or constrain that will make it impossible to run 2
services on same node, but I don't want any of that, as in
catastrophical scenarios when services would have to be located together
on same node, this would instead disable it.

Essentially what I want is for service to be always started on preferred
node when it is possible, but if it's not possible (eg. node is down) it
would freely run on any other node, with no restrictions and when node
is back up, it would migrate back.

How can I do that?