I suppose by leader you mean coordinator (a jgroups concept).

One way is to use the jboss-cli in scripting, for instance run this script to find out whether the current node is the coordinator:

[rhusar@ribera x]$ ./bin/jboss-cli.sh -c --controller=127.0.0.1:10190 "/subsystem=jgroups/channel=ee/protocol=pbcast.GMS:read-attribute(name=coord)"

{

    "outcome" => "success",

    "result" => false

}

to find out the coordinator from any node, you could use

[rhusar@ribera x]$ ./bin/jboss-cli.sh -c --controller=127.0.0.1:10190 "/subsystem=jgroups/channel=ee/protocol=pbcast.GMS:read-attribute(name=members)"

{

    "outcome" => "success",

    "result" => "(2) node3,node2"

}

where the 1st node name is the coordinator.