Vagrant is an automation tool with a domain-specific language (DSL) that is used to automate the creation of VMs and VM environments. The idea is that a user can create a set of instructions, using Vagrant’s DSL, that will set up one or more VMs and possibly configure those VMs
Every time the user uses the pre-created set of instructions, the end result will look exactly the same. This can be beneficial for a number of use cases, including developers who want a consistent development environment or for demo environment.
Vagrant makes this work by using a number of different components:
Providers: These are the “back end” of Vagrant. Vagrant itself doesn’t provide any virtualization functionality; it relies on other products to do the heavy lifting. Providers are how Vagrant interacts with the products that will do the actual virtualization work. A provider could be VirtualBox (included by default with Vagrant), VMware Fusion, Hyper-V, vCloud Air, or AWS, just to name a few.
Boxes: At the heart of Vagrant are boxes. Boxes are the predefined images that are used by Vagrant to build the environment according to the instructions provided by the user. A box may be a plain OS installation, or it may be an OS installation plus one or more applications installed. Boxes may support only a single provider or may support multiple providers (for example, a box might only work with VirtualBox, or it might support VirtualBox and VMware Fusion).
Vagrantfile: The Vagrantfile contains the instructions from the user, expressed in Vagrant’s DSL, on what the environment should look like—how many VMs, what type of VM, the provider, how they are connected, etc. Vagrantfiles are so named because the actual filename is Vagrantfile. The Vagrant DSL (and therefore Vagrantfiles) are based on Ruby.
A very simple example of a Vagrantfile:
VAGRANTFILE_API_VERSION = "2"
Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
# Box
config.vm.box = "ubuntu/precise64"
config.vm.box_url = "http://cloud-images.ubuntu.com/vagrant/precise/current/precise-server-cloudimg-amd64-vagrant-disk1.box"
# Shared folders
config.vm.synced_folder ".", "/vagrant"
