config.vm.customize is deprecated in favor of config.vm.provider

[shurane]

Well, that's the output I get from example3, but I'm guessing they all have it.

Here's output:

There were warnings and/or errors while loading your Vagrantfile
for the machine 'default'.

Your Vagrantfile was written for an earlier version of Vagrant,
and while Vagrant does the best it can to remain backwards
compatible, there are some cases where things have changed
significantly enough to warrant a message. These messages are
shown below.

Warnings:
* `config.vm.customize` calls are VirtualBox-specific. If you're
using any other provider, you'll have to use config.vm.provider in a
v2 configuration block.

[stvnwrgs]

replace

  node_config.vm.customize [
        'modifyvm', :id,
        '--name', node[:hostname],
        '--memory', memory.to_s
      ]

with

node_config.vm"virtualbox" do |v|
        v.customize[
            'modifyvm', :id,
            '--name', node[:hostname],
            '--memory', memory.to_s
          ]
      end