How to configure timezone for GrayLog2 on Ubuntu

Below are the two steps to configure time zone on GrayLog2 server, installed on Ubuntu deployed as virtual appliance.
$sudo graylog-ctl set-timezone <zone acronym>
check time zone list here
Restart or reconfigure the graylog service by this command
$ sudo graylog-ctl reconfigure
$ sudo graylog-ctl restart graylog-server