To make future Drupal VM updates easier to integrate with an existing project, you might consider the more complex setup of installing Drupal VM as a composer dependency. Using a delegating Vagrantfile you are able to run vagrant commands anywhere in your project as well as separate your custom configuration files from Drupal VM's own files.

Add Drupal VM as a Composer dependency

Add Drupal VM as a development dependency to your composer.json.

composer require --dev geerlingguy/drupal-vm

Setup your configuration files

Add and configure the config.yml anywhere you like, in this example we place it in a config/ directory.

Note: This will be the directory where Drupal VM looks for other local configuration files as well. Such as drupal_build_makefile and local.config.yml.

├── composer.json
├── config/
│   ├── config.yml
│   ├── local.config.yml
│   └── Vagrantfile.local
├── docroot/
│   ├── ...
│   └── index.php
└── vendor/
    ├── ...
    └── geerlingguy/
        └── drupal-vm/

Change the build strategy to use your composer.json file by setting:

drupal_build_composer_project: false
drupal_build_composer: true
drupal_composer_path: false
drupal_composer_install_dir: "/var/www/drupalvm"
drupal_core_path: "{{ drupal_composer_install_dir }}/docroot"

If you intened to use the devel module, it must be added as a requirement to your composer.json file. Alternatively, if you do not intend to use it remove it from drupal_enabled_modules in your config.yml file:

drupal_enabled_modules: []

Create a delegating Vagrantfile

Create a delegating Vagrantfile that will catch all your vagrant commands and send them to Drupal VM's own Vagrantfile. Place this file in your project's root directory.

# The absolute path to the root directory of the project. Both Drupal VM and
# the config file need to be contained within this path.
ENV['DRUPALVM_PROJECT_ROOT'] = "#{__dir__}"
# The relative path from the project root to the config directory where you
# placed your config.yml file.
ENV['DRUPALVM_CONFIG_DIR'] = "config"
# The relative path from the project root to the directory where Drupal VM is located.
ENV['DRUPALVM_DIR'] = "vendor/geerlingguy/drupal-vm"

# Load the real Vagrantfile
load "#{__dir__}/#{ENV['DRUPALVM_DIR']}/Vagrantfile"

When you issue vagrant commands anywhere in your project tree this file will be detected and used as a delegator for Drupal VM's own Vagrantfile.

Your project structure should now look like this:

├── Vagrantfile
├── composer.json
├── config/
│   ├── config.yml
│   ├── local.config.yml
│   └── Vagrantfile.local
├── docroot/
│   ├── ...
│   └── index.php
└── vendor/
    ├── ...
    └── geerlingguy/
        └── drupal-vm/

Provision the VM

Finally provision the VM using the delegating Vagrantfile.

vagrant up

Important: you should never issue vagrant commands through Drupal VM's own Vagrantfile from now on. If you do, it will create a secondary VM in that directory.

Drupal VM in a subdirectory without composer

If you're not using composer in your project you can still download Drupal VM (or add it as a git submodule) to any subdirectory in your project. As an example let's name that directory box/.

├── docroot/
│   ├── ...
│   └── index.php
└── box/
    ├── ...
    ├── default.config.yml
    └── Vagrantfile

Configure your config.yml as mentioned in the composer section above.

post_provision_scripts:
  # The default provided in `default.config.yml`:
  - "../../examples/scripts/configure-solr.sh"
  # With Drupal VM in a toplevel subdirectory
  - "{{ config_dir }}/../examples/scripts/configure-solr.sh"

Your directory structure should now look like this:

├── Vagrantfile
├── config/
│   ├── config.yml
│   ├── local.config.yml
│   └── Vagrantfile.local
├── docroot/
│   ├── ...
│   └── index.php
└── box/
    ├── ...
    ├── default.config.yml
    └── Vagrantfile

Provision the VM using the delegating Vagrantfile.

vagrant up