こんな感じでどうでしょう

Vagrantfile

Vagrant.require_version ">= 1.5.0"

Vagrant.configure("2") do |config|
  config.vm.box = "hashicorp/precise64"

  # Attach the current directory for Packer and Ansible
  config.vm.synced_folder ".", "/vagrant"

  # Install Packer
  config.vm.provision :shell, :inline => <<-PREPARE
    apt-get -y update
    apt-get install -y wget unzip curl

    mkdir -p /home/vagrant/packer
    cd /home/vagrant/packer
    if [ ! -e 0.5.2_linux_amd64.zip ]; then
      wget https://dl.bintray.com/mitchellh/packer/0.5.2_linux_amd64.zip
      unzip 0.5.2_linux_amd64.zip
      echo "export PATH=$PATH:/home/vagrant/packer" > /home/vagrant/.bashrc
    fi
  PREPARE

  # Use Docker provisioner to install Docker
  config.vm.provision :docker do |d|
    d.pull_images "ubuntu:13.10"
  end

  # Run Packer
  config.vm.provision :shell, :inline => <<-PACKER
    cd /vagrant
    packer build template.json
  PACKER

  # Check results
  config.vm.provision :shell, :inline => <<-RESULTS
    docker images

    docker run hexa/ubuntu/base:0.1 /opt/python/2.7.6/bin/python -V

    docker run hexa/ubuntu/base:0.1 /opt/ruby/2.1.1/bin/ruby -v
  RESULTS
end