message 匹配不上grok正则 也会写入到elasticsearch

{
       "message" => "scan test 20161201","@version" => "1","@timestamp" => "2016-12-01T05:17:39.018Z","path" => "/data01/gw/gw-app1-192.168.5.116-2016-12-01","host" => "Vsftp","type" => "gw-app-iis","tags" => [
        [0] "_grokparsefailure"
    ]
}


即使logstash 匹配不上,也会写入到elasticsearch