Vagrantpress + composer

Unfortunately you can’t use Vagrantpress and Composer directly together easily. Half of Vagrantpress is the WordPress setup itself which isn’t compatible. If you still wanted to leverage the base work Vagrantpress has done with PHP, Apache, MySQL etc, you could fork it and modify their WP module found here: https://github.com/chad-thompson/vagrantpress/blob/master/puppet/modules/wordpress/manifests/init.pp

It would still require a decent amount of changes though since you’d need to install Composer, modify their wp-config.php (the ones outlined in the Roots blog post), and run composer install instead of downloading the WP tar.gz.

It might just be easier to built a custom LAMP style Vagrant file with https://puphpet.com/ and then write your own manifests for the WP/Composer part.