title: How to exclude specific logs from docker in fluentd when using match tag?
body: <p>I use docker to send logs to <code>fluentd</code>. The load of logs from modules is so huge that disk space gets full within 3 to 4 days. The <code>fluentd</code> config looks like:</p>
  
  <pre><code>&lt;source&gt;
    @type  forward
    @id    input1
    @label @mainstream
    port  24224
  &lt;/source&gt;
  
  &lt;filter **&gt;
    @type stdout
  &lt;/filter&gt;
  
  &lt;label @mainstream&gt;
   &lt;match project_docker**mangox:latest**&gt;
      @type elasticsearch
      host 172.16.131.102
      port 9200
      index_name project_mangox
      type_name mangox
      logstash_format true
      logstash_prefix project_mangox
      logstash_dateformat %Y%m%d
      buffer_queue_full_action drop_oldest_chunk
    &lt;/match&gt;
  &lt;/label&gt;
  </code></pre>
  
  <p>I have gone through some documentation in <code>fluentd</code> to see if there is any and see that I can use <a href="https://docs.fluentd.org/v0.12/articles/filter_grep" rel="nofollow noreferrer">filter_grep</a>, the problem is that I use <code>match</code> instead of <code>filter</code> tag. </p>
  
  <p><strong>The question is</strong>  how can I use something similar to grep in <code>match</code>? Or can I even use <code>filter_grep</code> in match tag? How is that possible?</p>