title: Why fluentd grep exlude filter doesn't work?
body: <p>Why isn't this filtering?</p>
  
  <pre><code>&lt;source&gt;
    @type dummy
    tag kubernetes.log
    dummy [{"log":"1234", "stream":"stdout", "kubernetes":{"container_name":"log-collector-fluentd" }, "time":"2017-05-04T15:01:21.000000000Z"}]
  &lt;/source&gt;
  
  &lt;filter kubernetes.**&gt;
     @type grep
     exclude1 kubernetes.container_name log-collector-fluentd
  &lt;/filter&gt;
  
  &lt;match kubernetes.**&gt;
    @type             stdout
  &lt;/match&gt;
  </code></pre>
  
  <p>Testing:</p>
  
  <pre><code>$ /opt/td-agent/embedded/bin/ruby -- /usr/sbin/td-agent -c /fluentd.conf
  2017-05-05 06:22:58 +0000 kubernetes.log: {"log":"1234","stream":"stdout","kubernetes":{"container_name":"log-collector-fluentd"},"time":"2017-05-04T15:01:21.000000000Z"}
  </code></pre>