Create a vagrant box with chef server provisioning and automatic client and node cleanup on the server when the vagrant box gets destroyed. All necessary api keys and config options are taken from environment variables. The knife.rb must live inside a .chef directory besides the Vagrantfile.

bash_profile

# Opscode chef configurations.
export KNIFE_CHEF_SERVER="https://chef-api.example.com"
export KNIFE_CLIENT_KEY="$HOME/.chef/client.pem"
export KNIFE_NODE_NAME="myclient"
export KNIFE_VALIDATION_CLIENT_NAME="chef-validator"
export KNIFE_VALIDATION_CLIENT_KEY="$HOME/.chef/chef-validator.pem"

knife.rb

# Logging.
log_level                         :debug
log_location                      STDOUT

# Chef server configuration.
chef_server_url                   "#{ENV['KNIFE_CHEF_SERVER']}"
client_key                        "#{ENV['KNIFE_CLIENT_KEY']}"
node_name                         "#{ENV['KNIFE_NODE_NAME']}"
validation_client_name            "#{ENV['KNIFE_VALIDATION_CLIENT_NAME']}"
validation_key                    "#{ENV['KNIFE_VALIDATION_CLIENT_KEY']}"

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :
require 'chef'

Chef::Config.from_file(File.join(File.dirname(__FILE__), '.chef', 'knife.rb'))

vms = {
  "testbox" => {
    :box => "precise64",
    :ipaddress => "192.168.33.10",
    :run_list => "role[base]"
  }
}

Vagrant::Config.run do |global_config|
  vms.each_pair do |name, options|
    global_config.vm.define name do |config|
      # Every Vagrant virtual environment requires a box to build off of.
      config.vm.box = options[:box]
      vm_name = "vagrant-#{name}-#{ENV['USER']}"

      # Boot with a GUI so you can see the screen. (Default is headless)
      # config.vm.boot_mode = :gui

      # Assign this VM to a host-only network IP, allowing you to access it
      # via the IP. Host-only networks can talk to the host machine as well as
      # any other machines on the same network, but cannot be accessed (through this
      # network interface) by any external networks.
      config.vm.network :hostonly, options[:ipaddress]
      config.vm.host_name = vm_name

      # Enable provisioning with chef server, specifying the chef server URL,
      # and the path to the validation key (relative to this Vagrantfile).
      config.vm.provision :chef_client do |chef|
        chef.chef_server_url = Chef::Config[:chef_server_url]
        chef.log_level = Chef::Config[:log_level]
        chef.node_name = vm_name
        chef.validation_key_path = Chef::Config[:validation_key]
        chef.validation_client_name = Chef::Config[:validation_client_name]
        chef.environment = "development"
        run_list = []
        run_list << ENV['CHEF_RUN_LIST'].split(",") if ENV.has_key?('CHEF_RUN_LIST')
        chef.run_list = [options[:run_list].split(","), run_list].flatten
      end
    end
  end
end


module Vagrant
  module Provisioners
    class Base
      require 'chef'
      require 'chef/config'
      require 'chef/knife'
    end

    class ChefClient
      ::Chef::Config.from_file(File.join(File.dirname(__FILE__), '.chef', 'knife.rb'))

      def cleanup
        node = env[:vm].config.vm.host_name

        env[:ui].info "Attempting to clean up client '#{node}' on chef server."
        begin
          ::Chef::REST.new(::Chef::Config[:chef_server_url]).delete_rest("clients/#{node}")
        rescue Net::HTTPServerException => e
          if e.message == '404 "Not Found"'
            env[:ui].info "Client '#{node}' not found."
          else
            env[:ui].error "An error occured. You will have to remove the client manually."
          end
        rescue Exception => e
            env[:ui].error "An error occured. You will have to remove the client manually."
        else
          env[:ui].info "Client '#{node}' successfully removed from chef server."
        end

        env[:ui].info "Attempting to clean up node '#{node}' on chef server."
        begin
          ::Chef::REST.new(::Chef::Config[:chef_server_url]).delete_rest("nodes/#{node}")
        rescue Net::HTTPServerException => e
          if e.message == '404 "Not Found"'
            env[:ui].info "Node '#{node}' not found."
          else
            env[:ui].error "An error occured. You will have to remove the node manually."
          end
        rescue Exception => e
            env[:ui].error "An error occured. You will have to remove the node manually."
        else
          env[:ui].info "Node '#{node}' successfully removed from chef server."
        end
      end
    end
  end
end

The code is based on the blogpost MultiVM Vagrantfile for Chef by Joshua Timberman, the Chef Server Sandbox by spheromak and the gist by cassiano.