The VirtualBox provider exposes some additional configuration options that allow you to more finely control your VirtualBox-powered Vagrant environments.

GUI vs. Headless

By default, VirtualBox machines are started in headless mode, meaning there is no UI for the machines visible on the host machine. Sometimes, you want to have a UI. Common use cases include wanting to see a browser that may be running in the machine, or debugging a strange boot issue. You can easily tell the VirtualBox provider to boot with a GUI:

config.vm.provider "virtualbox" do |v|
  v.gui = true

Virtual Machine Name

You can customize the name that appears in the VirtualBox GUI by setting the name property. By default, Vagrant sets it to the containing folder of the Vagrantfile plus a timestamp of when the machine was created. By setting another name, your VM can be more easily identified.

config.vm.provider "virtualbox" do |v| = "my_vm"

VBoxManage Customizations

VBoxManage is a utility that can be used to make modifications to VirtualBox virtual machines from the command line.

Vagrant exposes a way to call any command against VBoxManage just prior to booting the machine:

config.vm.provider "virtualbox" do |v|
  v.customize ["modifyvm", :id, "--cpuexecutioncap", "50"]

In the example above, the VM is modified to have a host CPU execution cap of 50%, meaning that no matter how much CPU is used in the VM, no more than 50% would be used on your own host machine. Some details:

  • The :id special parameter is replaced with the ID of the virtual machine being created, so when a VBoxManage command requires an ID, you can pass this special parameter.

  • Multiple customize directives can be used. They will be executed in the order given.

There are some convenience shortcuts for memory and CPU settings:

config.vm.provider "virtualbox" do |v|
  v.memory = 1024
  v.cpus = 2