logstash @timestamp 八小時問題

filter {
  date {
    match => ["message","UNIX_MS"]
    target => "@timestamp"   
  }
 ruby { 
   code => "event.set('timestamp', event.get('@timestamp').time.localtime + 8*60*60)" 
 }
 ruby {
   code => "event.set('@timestamp',event.get('timestamp'))"
 }
 mutate {
   remove_field => ["timestamp"]
 }
}