userdata.sh

#!/bin/bash

export DEBIAN_FRONTEND=noninteractive

# reduce the server load and free as much memory as we can
service unicorn stop
service nginx stop
service postgresql stop

# remove the old postgresql
apt-get -y remove postgresql-* nginx-*

apt-get -y update
apt-get -y upgrade
apt-get -y dist-upgrade
apt-get -y install update-manager-core
do-release-upgrade -f DistUpgradeViewNonInteractive

# install the new postgresql
apt-get -y install postgresql-9.5 nginx