There's an open issue [1]. A scripting interface has since been added [2], and updated [3], so there's progress.

[1] https://github.com/hashicorp/vagrant/issues/12518

[2] https://github.com/hashicorp/vagrant/issues/12518#issuecomme...

[3] https://github.com/hashicorp/vagrant/issues/12518#issuecomme...