title: groking nested information in logstash
body: <p>My log events look like this:</p>
  
  <pre><code>WARN 12 Dec 00:11:12 slow:[Task[Task-Name 20 ms],Task[Task-Name 30 ms]], time = 1234
  </code></pre>
  
  <p>This means that some slow tasks which may be nested are logged.</p>
  
  <p>Is there any chance to create as many fields I need (= number of tasks which differs at each event logged) by an grok filter?</p>
  
  <p>Or should I have to write my own filter and at least how can I access these fields?</p>