*`var.convert_timezone`*::

If this option is enabled, Filebeat reads the local timezone and uses it at log
parsing time to convert the timestamp to UTC. The local timezone is also added
in each event in a dedicated field (`beat.timezone`). The conversion is only
possible in Elasticsearch >= 6.1. If the Elasticsearch version is less than 6.1,
the `beat.timezone` field is added, but the conversion to UTC is not made.  The
default is `false`.