[root@controller-01 ~]# cat /var/log/logstash/logstash.err
Exception in thread ">output" org.elasticsearch.discovery.MasterNotDiscoveredException: waited for [30s]
        at org.elasticsearch.action.support.master.TransportMasterNodeOperationAction$4.onTimeout(org/elasticsearch/action/support/master/TransportMasterNodeOperationAction.java:164)
        at org.elasticsearch.cluster.ClusterStateObserver$ObserverClusterStateListener.onTimeout(org/elasticsearch/cluster/ClusterStateObserver.java:231)
        at org.elasticsearch.cluster.service.InternalClusterService$NotifyTimeout.run(org/elasticsearch/cluster/service/InternalClusterService.java:560)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(java/util/concurrent/ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(java/util/concurrent/ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(java/lang/Thread.java:745)