In some situations, primarily with automated deployments, it makes sense to
install curator on every node. But you wouldn’t want it to run on each node.
--master-only flag, this is possible. It tests for, and will only
continue running on the node that is the elected master.
--master-onlyOnly operate on elected master node.
This flag must come before any command.
Operate only on the master node:
curator --master-only <<command>> <<flags>>