Riak cluster Vagrantfile to offer an alternative to Basho Chef+Vagrant blog post suggestion and receive feedback at http://blog.basho.com/2011/02/04/creating-a-local-riak-cluster-with-vagrant-and-chef/

Vagrantfile.rb

# Offering alternative Chef + Vagrant Riak cluster setup to the following blog post at basho:
# http://blog.basho.com/2011/02/04/creating-a-local-riak-cluster-with-vagrant-and-chef/

# Assumes Vagrant 0.7.0+ and VirtualBox 4.0+

# Now you should be able to launch your X (where X=4 in this case) vagrant VMs with the following:
# % vagrant up db1
# % vagrant up db2
# % vagrant up db3
# % vagrant up db4
# % vagrant up webapp

Vagrant::Config.run do |config|
  config.ssh.username = "sudoableuser"
  config.ssh.max_tries = 25
  config.vm.share_folder "tint", "/releases", "rel", :auto => true
  config.vm.share_folder "chef", "/vm/root/path", "your/chef/root", :auto => true

  (1..4).each do |index|
    config.vm.define "db#{index}".to_sym do |cfg|
      cfg.vm.box = "my-server-box"
      cfg.vm.host_name = "db#{index}"
      cfg.vm.customize do |vm|
        vm.name = "My Riak DB#{index} VM"
        vm.memory_size = 512
        vm.network "33.33.33.#{index}"
        vm.forward_port "ssh", 22, "220#{index}".to_i
      end
      cfg.vm.provision :chef_solo do |chef|
        # fill in here, I usually use CHEF_ROOT="/var/tmp/chef"
        chef.provisioning_path = "/path/to/chef/root"
        chef.cookbooks_path = [:vm, "cookbooks"]
        chef.roles_path = [:vm, "roles"]
        chef.add_role :my_db
        # HOSTS might be something like: ["app1", "app2", "app3"]
        # DOMAIN would be something like: "mydomainname.tld"
        # RELEASE_DIR would be something like: "/releases/name_of_otp_release"
        chef.json.merge!  :hosts => HOSTS, :domain => DOMAIN,
                          :release_dir => RELEASE_DIR
      end
      # add share_folder to share your webapp code below...
    end
  end

  config.vm.define :webapp do |cfg|
    cfg.vm.box = "my-server-box"
    cfg.vm.host_name = "www"
    cfg.vm.customize do |vm|
      vm.name = "My WebApp VM"
      vm.memory_size = 512
      vm.network "33.33.33.5"
      vm.forward_port "ssh", 22, 2205
    end
    cfg.vm.provision :chef_solo do |chef|
      chef.provisioning_path = "/path/to/chef/root"
      chef.cookbooks_path = [:vm, "cookbooks"]
      chef.roles_path = [:vm, "roles"]
      chef.add_role :my_db
      # HOSTS might be something like: ["app1", "app2", "app3"]
      # DOMAIN would be something like: "mydomainname.tld"
      # RELEASE_DIR would be something like: "/releases/name_of_otp_release"
      chef.json.merge!  :hosts => HOSTS, :domain => DOMAIN,
                        :release_dir => RELEASE_DIR
    end
    # add share_folder to share your webapp code below...
  end  
end

Awesome! Note that with host-only networking you have two interfaces, so you still need to specify the node name, otherwise it will be riak@10.0.2.15 (or similar), which will not be reachable by the other nodes.

I just noticed the comment and realized I didn't include some important parts of my Vagrantfile. Will need to fix momentarily.