Ubuntu 16.04 vagrantfile with postgresql 9.5

vagrantfile.rb

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant.configure(2) do |config|


  config.vm.box = "ubuntu/xenial64"

  $script = <<SCRIPT
sudo echo "deb http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -c | awk '{print $2}')-pgdg main" > /etc/apt/sources.list.d/pgdg.list
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7FCC7D46ACCC4CF8
sudo apt-get update
sudo apt install -y postgresql-9.5
SCRIPT

  config.vm.provider "virtualbox" do |vb|
    vb.gui = false

    vb.memory = "2048"
  end

 config.vm.provision :shell, inline: $script

  config.vm.define "master" do |master|
    master.vm.hostname = "masterdb"
    master.vm.network "private_network", ip: "192.168.100.100"
  end

  config.vm.define "slave" do |slave|
    slave.vm.hostname = "slavedb"
    slave.vm.network "private_network", ip: "192.168.100.200"
  end
end