set_hostname.sh

#!/bin/bash
#
# this script expects user data field set like below.
#
#==========================
#hostname hogehostname
#somekey fugafuga
#==========================
#

USERDATA=`curl -s http://169.254.169.254/latest/user-data`
HOSTNAME=`echo ${USERDATA} | awk '/^hostname/{print $2}'`

if [ "${HOSTNAME}" != "" ]; then
    echo "set hostname to ${HOSTNAME}"
    hostname ${HOSTNAME}
else
    echo "no hostname record found on user data"
fi