chef-solo ssl warning when provisioning

This warning was introduced in Chef 11.12.0. See the release notes for details:

When ssl_verify_mode is set to :verify_none, Chef will print a
warning. Use knife ssl check to test SSL connectivity and then add
ssl_verify_mode :verify_peer to your configuration file to fix the
warning. Though :verify_none is currently the default, this will be
changed in a future release, so users are encouraged to be proactive in
testing and updating their SSL configuration.

To fix this warning in Vagrant, you have to amend the solo.rb config file it creates in the VM. With Vagrant you can use the custom_config_path option for that.

You can thus amend your Vagrantfile like this:

Vagrant.configure("2") do |config|
  config.vm.provision "chef_solo" do |chef|
    # the next line is added
    chef.custom_config_path = "Vagrantfile.chef"
  end
end

This makes Vagrant include the contents of the local file Vagrantfile.chef into the generated solo.rb, the file thus needs to be present on your host system, not the VM.

Then, create a new file Vagrantfile.chef in the directory where you also keep your Vagrantfile with the following content:

Chef::Config.ssl_verify_mode = :verify_peer

The next run of vagrant provision should no longer print the warning.