Shell script to set friendly hostnames for AWS ec2instances

setHostname.sh

#!/bin/bash
# brady [r3dact3d]
echo '### Setting Hostname ###'
OLD_HOSTNAME=`hostname`
if [[ $OLD_HOSTNAME != "master" || "node" || "etcd" || "ansible" ]]; then
  # Change first field here depending on section of UserData for 'master|ectd|node|ansible'
  NEW_HOSTNAME=ansible-`hostname | cut -d- -f4,5`
  # Set hostname on ec2 instance
  hostnamectl set-hostname "$NEW_HOSTNAME"
  # Set hostname in /etc/sysconfig/network config
  sed -i "s/HOSTNAME=.*/HOSTNAME=$NEW_HOSTNAME/g" /etc/sysconfig/network
  # Set hostname in /etc/hosts config
  if [ -n "$( grep "$OLD_HOSTNAME" /etc/hosts )" ]; then
    sed -i "s/$OLD_HOSTNAME/$NEW_HOSTNAME/g" /etc/hosts
  else
    echo -e "$( hostname -I | awk '{ print $1 }' )\t$NEW_HOSTNAME" >> /etc/hosts
  fi
  echo "### Set Hostname to: $NEW_HOSTNAME ###"
else
  echo "### Hostname already includes role ###"
fi