title: Filebeat to Logstash timezone issue
body: <p>Using Filebeat, and Logstash 7.9.
  Customer logfiles have timestamps in local timezone.
  Want to let Logstash know in which timezone filebeat lives.
  Am able to do that via adding:</p>
  <pre><code>processors:
    - add_locale:
        format: abbreviation
  </code></pre>
  <p>in filebeat.yml, and in logstash filter using the event.timezone via:</p>
  <pre><code>    grok {
            match =&gt; { &quot;message&quot; =&gt; &quot;%{DATESTAMP:logdate} %{GREEDYDATA:jsonmess}&quot;}
      }
      date {
        match =&gt; [&quot;logdate&quot;, &quot;yy-MM-dd HH:mm:ss,SSS&quot;]
        timezone =&gt; &quot;{{ event.timezone }}&quot;
      }
  </code></pre>
  <p>Problem is that filebeat options for the timezone format are &quot;offset&quot; and &quot;abbrevation&quot;, but logstash expects only &quot;canonical id's&quot; !
  How can i make this work ?</p>