Elasticsearch5.1.1 after install x-pack ， as long as the configuration of heading "discovery" configuration, eg discovery.zen.ping.unicast.hosts ；discovery.zen.minimum_master_nodes ...
So the following fault.
skipping exporter [default_local] as it isn't ready yet
2017-03-01T16:22:33,752[o.e.x.m.AgentService ] [node-1] exception when exporting documents
org.elasticsearch.xpack.monitoring.exporter.ExportException: exporters are either not ready or faulty
at org.elasticsearch.xpack.monitoring.exporter.Exporters.export(Exporters.java:188) ~[x-pack-5.1.1.jar:5.1.1]
at org.elasticsearch.xpack.monitoring.AgentService$ExportingWorker.run(AgentService.java:208) [x-pack-5.1.1.jar:5.1.1]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]