---
page_title: "Configuration - VirtualBox Provider"
sidebar_current: "virtualbox-configuration"
---

# Configuration

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
end
```

## 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.

```ruby
config.vm.provider "virtualbox" do |v|
  v.name = "my_vm"
end
```

## Linked Clones

By default new machines are created by importing the base box. For large
boxes this produces a large overhead in terms of time (the import operation)
and space (the new machine contains a copy of the base box's image).
Using linked clones can drastically reduce this overhead.

Linked clones are based on a master VM, which is generated by importing the
base box only once the first time it is required. For the linked clones only 
differencing disk images are created where the parent disk image belongs to
the master VM.

```ruby
config.vm.provider "virtualbox" do |v|
  v.use_linked_clone = true
end
```

<div class="alert alert-info">
	<strong>Note:</strong> the generated master VMs are currently not removed
	automatically by Vagrant. This has to be done manually. However, a master
	VM can only be removed when there are no linked clones connected to it.
</div>

## VBoxManage Customizations

[VBoxManage](http://www.virtualbox.org/manual/ch08.html) 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:

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

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:

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