什么可以解释ElasticSearch 2.4不接受通过curl创建观察者？

Question

[root@elk01 ~]# curl -XPUT 'http://127.0.0.1:9200/_watcher/watch/log_error_watch' -d '{
  "trigger" : {
    "schedule" : { "interval" : "10s" }
  },
  "input" : {
    "search" : {
      "request" : {
        "indices" : [ "logs" ],
        "body" : {
          "query" : {
            "match" : { "message": "error" }
          }
        }
      }
    }
  }
}'
{"error":{"root_cause":[{"type":"invalid_index_name_exception","reason":"Invalid index name [_watcher], must not start with '_', '-', or '+'","index_uuid":"_na_","index":"_watcher"}],"type":"invalid_index_name_exception","reason":"Invalid index name [_watcher], must not start with '_', '-', or '+'","index_uuid":"_na_","index":"_watcher"},"status":400}
[root@elk01 ~]#

我们正在使用Kibana 4.6和ES 2.4，并希望设置来自Heartbeat，Metricbeat和Filebeat的数据警报。