Vagrantfile, multi machine with ssh password less and hostname over private network.

Vagrantfile

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

Vagrant.require_version ">= 1.6.0"

baseip="192.168.187"

boxes = [
    {
        :name => "master",
        :eth1 => "#{baseip}.#{10}",
        :mem =>  "2048",
        :cpu =>  "2"
    },
    {
        :name => "node1",
        :eth1 => "#{baseip}.#{11}",
        :mem =>  "1024",
        :cpu =>  "1"
    },
    {
        :name => "node2",
        :eth1 => "#{baseip}.#{12}",
        :mem =>  "1024",
        :cpu =>  "1"
    }
]

numnodes=boxes.size

#global script
$global = <<SCRIPT

#check for private key for vm-vm comm
[ -f /vagrant/id_rsa ] || {
  ssh-keygen -t rsa -f /vagrant/id_rsa -q -N '' -C vagrant@master
}

#deploy key
[ -f ${HOME}/.ssh/id_rsa ] || {
    cp /vagrant/id_rsa ${HOME}/.ssh/id_rsa
    chmod 0600 ${HOME}/.ssh/id_rsa
}

#allow ssh passwordless
grep 'vagrant@master' ~/.ssh/authorized_keys &>/dev/null || {
  cat /vagrant/id_rsa.pub >> ~/.ssh/authorized_keys
  chmod 0600 ~/.ssh/authorized_keys
}

#exclude node* from host checking
cat > ~/.ssh/config <<EOF
Host node*
   StrictHostKeyChecking no
   UserKnownHostsFile=/dev/null
EOF

#populate /etc/hosts
for x in {11..#{10+numnodes-1}}; do
  grep #{baseip}.${x} /etc/hosts &>/dev/null || {
      echo #{baseip}.${x} node${x##?} | sudo tee -a /etc/hosts &>/dev/null
  }
done

#end script
SCRIPT

Vagrant.configure("2") do |config|
  config.vm.box = "ubuntu/xenial64"
  config.vm.provision "shell", privileged: false, inline: $global
  prefix="node"
  #node box
  boxes.each do |opts|
    vm_name = opts[:name]
    config.vm.define vm_name do |node|
      node.vm.hostname = vm_name
      ip=opts[:eth1]
      node.vm.network "private_network", ip: ip
      config.vm.provider "vmware_fusion" do |v|
          v.vmx["memsize"] = opts[:mem]
          v.vmx["numvcpus"] = opts[:cpu]
      end
      config.vm.provider "virtualbox" do |v|
          v.customize ["modifyvm", :id, "--memory", opts[:mem]]
          v.customize ["modifyvm", :id, "--cpus", opts[:cpu]]
      end
    end
  end
end