Introducing Vagrant

Have you ever heard the following? “Welcome to the team! Here’s a list of 15 applications to install, the instructions are in the team room, somewhere. See you in a week!” Or: “What do you mean it broke production, it runs fine on my machine?” Or: “Why is this working on her machine and his machine, but not my machine?”

Development environments are becoming more complex, with more moving parts and tricky dependencies. Virtualization has been a huge boon for the IT industry in saving costs, increasing flexibility and maintaining control over complex environments. Rather than focusing on virtualization on the delivery side, let’s look at how you can provide that flexibility and control to developers to manage multiple development environments easily using Vagrant.

What Is Vagrant?

Vagrant is an open-source (MIT) tool for building and managing virtualized development environments developed by Mitchell Hashimoto and John Bender. Vagrant manages virtual machines hosted in Oracle VirtualBox, a full x86 virtualizer that is also open source (GPLv2).

A virtual machine is a software implementation of a computer, running a complete operating system stack on a virtualizer. It is a full implementation of a computer with a virtual disk, memory and CPU. The machine running the virtualizer is the Host system. The virtual machine running on the virtualizer is the Guest system. As far as the Guest operating system is concerned, it is running on real hardware. From the perspective of the Host, all of the Guest’s resources are used by the virtualizer program. A Box, or base image, is the prepackaged virtual machine that Vagrant will manage.

Installing Vagrant

Starting in version 1.0, Vagrant provides two installation methods: packaged installers for supported platforms or a universal install with Ruby Gems. This article covers installation using Gems. This method has three parts: 1) install VirtualBox, 2) install Ruby and 3) install Vagrant itself.

VirtualBox is available from the VirtualBox home page with builds for Windows, OS X, Linux and Solaris. Note that Oracle provides the Oracle VM VirtualBox Extension Pack on the Download site that provides additional features to the virtualizer. The Extension Pack has a separate license (Personal Use and Evaluation License) and is not needed to use Vagrant, but if the Box you are using was created using the Extension Pack, you will need to install the Extension Pack as well.

Ruby is a popular dynamically typed object-oriented scripting language. Ruby is available out of the box in OS X, and most Linux distributions also have a Ruby package available. For Windows users, the RubyInstaller Project provides an easy way to install the Ruby runtime.

Ruby libraries and applications are available in packages called RubyGems or Gems. Ruby comes with a package management tool called gem. To install Vagrant, run the gem command:


> gem install vagrant

Vagrant is a command-line tool. Calling vagrant without additional arguments will provide the list of available arguments. I’ll visit most of these commands within this article, but here’s a quick overview:

  • init — create the base configuration file.
  • up — start a new instance of the virtual machine.
  • suspend — suspend the running guest.
  • halt — stop the running guest, similar to hitting the power button on a real machine.
  • resume — restart the suspended guest.
  • reload — reboot the guest.
  • status — determine the status of vagrant for the current Vagrantfile.
  • provision — run the provisioning commands.
  • destroy — remove the current instance of the guest, delete the virtual disk and associated files.
  • box — the set of commands used to add, list, remove or repackage box files.
  • package — used for the creation of new box files.
  • sshssh to a running guest.

The last thing you need to do in your installation is set up a base image. A Box, or base image, is the prepackaged virtual machine that Vagrant will manage. Use thebox command to add the Box to your environment. The vagrant box add command takes two arguments, the name you use to refer to the Box and the location of the Box:


> vagrant box add lucid32 http://files.vagrantup.com/lucid32.box

This command adds a new Box to the system called “lucid32” from a remotely hosted site over HTTP. Vagrant also will allow you to install a Box from the local filesystem:


> vagrant box add rhel5.7 rhel5.7-20120120-1223.box
[vagrant] Downloading with Vagrant::Downloaders::File...
[vagrant] Copying box to temporary location...
[vagrant] Extracting box...
[vagrant] Verifying box...
[vagrant] Cleaning up downloaded box...
> 

Now there are two Boxes installed:


>vagrant box list
lucid32
rhel5.7

It is important to note that you can reuse these base images. A Box can be the base for multiple projects without contamination. Changes in any one project will not change the other projects that share a Box. As you’ll see, changes in the base can be shared to projects easily. One of the powerful concepts about using Vagrant is that the development environment is now totally disposable. You persist your critical work on the Host, while the Guest can be reloaded quickly and provisioned from scratch.

Starting Vagrant

Create a directory on the Host as your starting point. This directory is your working directory. Vagrant will share this directory between the Guest and the Host automatically. Developers can edit files from their preferred Editors or IDEs without updating the Guest. Changes made in the Host or Guest are immediately visible to the user from either perspective:


> mkdir ProjectX
> cd ProjectX

To get started, you need a Vagrantfile. The Vagrantfile is to similar to a Makefile, a set of instructions that tells Vagrant how to build the Guest. Vagrant uses Ruby syntax for configuration. The simplest possible Vagrantfile would be something like this:


Vagrant::Config.run do |config|
  config.vm.box = "lucid32"
end

This configuration tells Vagrant to use all the defaults and the Box called lucid32. There actually are four Vagrantfiles that are read: the local version in the current directory, a user version in ~/.vagrant.d/, a Box version in the Box file and an initial config installed with the Gem. Vagrant reads these files starting with the Gem version and finishing with the current directory. In the case of conflicts, the most recent version wins, so the current directory overrides the ~/.vagrant.d, which overrides the Box version and so on. Users can create a new Vagrantfile simply by running:


> vagrant init 

This creates a Vagrantfile in the current directory. The generated Vagrantfile has many of the common configuration parameters with comments on their use. The file tries to be self-documenting, but additional information is available from the Vagrant Web site. To run most Vagrant commands, you need to be in the same directory as the Vagrantfile.

Let’s give it a try:


$ vagrant up
[default] Importing base box 'lucid32'...
[default] The guest additions on this VM do not match the install 
version of VirtualBox! This may cause things such as forwarded 
ports, shared folders, and more to not work properly. If any of 
those things fail on this machine, please update the guest 
additions and repackage the box.

Guest Additions Version: 4.1.0
VirtualBox Version: 4.1.8
[default] Matching MAC address for NAT networking...
[default] Clearing any previously set forwarded ports...
[default] Forwarding ports...
[default] -- 22 => 2222 (adapter 1)
[default] Creating shared folders metadata...
[default] Clearing any previously set network interfaces...
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] VM booted and ready for use!
[default] Mounting shared folders...
[default] -- v-root: /vagrant

Let’s break this down. I’m running with VirtualBox 4.1.8 and a Guest at 4.1.0. In this case it works smoothly, but the warning is there to help troubleshoot issues should they appear. Next, it sets up the networking for the Guest:


[default] Matching MAC address for NAT networking...
[default] Clearing any previously set forwarded ports...
[default] Forwarding ports...
[default] -- 22 => 2222 (adapter 1)

I used the default network setting of Network Address Translation with Port Forwarding. I am forwarding port 2222 on the Host to port 22 on the Guest. Vagrant starts the Guest in headless mode, meaning there is no GUI interface that pops up. For users who want to use the GUI version of the Guest, the option is available in the Vagrantfile to run within a window. Once the network is set up, Vagrant boots the virtual machine:


[default] VM booted and ready for use!
[default] Mounting shared folders...
[default] -- v-root: /vagrant

After the Guest has started, Vagrant will add the shared folder. Vagrant uses the VirtualBox extensions to mount the current folder (ProjectX in this case) as /vagrant. Users can copy and manipulate files from the Host OS in the ProjectX directory, and all the files and changes will be visible in the Guest. If the shared folder isn’t performing well because you have a large number of files, Vagrant does support using NFS. However, it does require that NFS is supported by both the Guest andHost systems. At this time, NFS is not supported on Windows Hosts.


		

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