Multi-machine Vagrantfile + ansible ... only one host is provisioned

Vagrant
1

I have a multi-machine environment (vagrant, virtualbox, ansible). When the provisioner step runs, only the first machine is actually updated - the subsequent machines show ‘ok’ and do not get the ansible tasks run. How can I ensure that as each host comes up that it gets provisioned – or even, wait to run provisioning till all machines are up?

My Vagrant file:

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

Vagrant.require_version ">= 1.7.0"
IMAGE_NAME = "minimal/xenial64"

boxes = [
        { :name => "test1", :ip => "172.31.254.10" },
        { :name => "test2", :ip => "172.31.254.11" },
        { :name => "test3", :ip => "172.31.254.12" },
        { :name => "test4", :ip => "172.31.254.13" },
        { :name => "test5", :ip => "172.31.254.14" },
        { :name => "test6", :ip => "172.31.254.15" }
]
Vagrant.configure("2") do |config|
    config.ssh.insert_key = false
    config.vm.box = IMAGE_NAME

    # Virtualbox configuration
    config.vm.provider "virtualbox" do |v|
        v.memory = 512
        v.cpus = 1
    end
    boxes.each do |opts|
        config.vm.define opts[:name] do |config|
            config.vm.hostname = opts[:name]
            config.vm.network :private_network, ip: opts[:ip]
            config.vm.provision "ansible" do |ansible|
                ansible.limit = "all"
                ansible.become = true
                ansible.verbose = "v"
                ansible.playbook = "test_lab.yml"
            end
        end
    end
end

and the very simple ansible playbook (just adds entries to /etc/hosts right now)

---
- name: Set up local dev environment using vagrant and ansible
  hosts: all
  become: yes
  gather_facts: no
  tasks:
    - name: change /etc/hosts
      lineinfile:
        path: '/etc/hosts'
        line: "{{ item.line }}"
        state: present
        backup: yes
      loop:
        - { regexp: '^172.31.254.10', line: '172.31.254.10 test1' }
        - { regexp: '^172.31.254.11', line: '172.31.254.11 test2' }
        - { regexp: '^172.31.254.12', line: '172.31.254.12 test3' }
        - { regexp: '^172.31.254.13', line: '172.31.254.13 test4' }
        - { regexp: '^172.31.254.14', line: '172.31.254.14 test5' }
        - { regexp: '^172.31.254.15', line: '172.31.254.15 test6' }