Franck Cuny @franckcuny

Software and Operation engineer.

Vagrant rocks

tl;dr

I've been toying with vagrant lately, and it really rocks. You should definitly give it a try. If you're only looking for some resources to get started with it, go there:

What is Vagrant

"Vagrant is a tool for building and distributing virtualized development environments." This sentence summarizes perfectly the project.

The idea is to use Chef on top of VirtualBox to deploy a VM like you would deploy a server in your production environment.

I won't go into the details to describe Chef and VirtualBox, but here is a quick reminder. Chef is a framework to deploy infrastructures. It's written in ruby, it uses cookbooks to describe how to deploy stuff, and VirtualBox is a virtualization software from Oracle.

A little disclaimer. I don't use Chef outside from vagrant, so I may say/do some stupid things. The aim of this tutorial is not about writing a recipe for Chef, but to show what you can do thanks to Chef. So don't hesitate to correct me in the comments if I'm doing some utterly stupid things.

The basic

To install vagrant, you'll need ruby and virtualbox. You have the basic instructions detailed here. This will explain how to install vagrant and how to fetch a base image.

Creating a first project

You'll probably want to start creating a new project now. For this tutorial, I'll create an image for presque.

% mkdir presque
% vagrant init

This will create a new image for your project, and create a new file in your directory: Vagrantfile. Modify this file to make it look like this:

Vagrant::Config.run do |config|
  config.vm.box = "base"
  config.vm.provisioner = :chef_solo
  config.chef.cookbooks_path = "cookbooks"
  config.chef.add_recipe("vagrant_main")
  config.vm.forward_port("web", 5000, 8080)
end

These instructions will:

  • tell vagrant to use the image named base (a lucid32 image by default)
  • use chef in solo mode
  • the recipes will be in a directory named cookbooks
  • the main recipe will be named vagrant_main
  • forward local HTTP port 4000 to 5000 on the VM

My recipes

Now we need to create or use some recipes. First we create our cookbooks directory:

% mkdir cookbooks
% mkdir -p cookbooks/vagrant_main/recipes

We need to add some cookbooks. You will find them on GitHub. Copy the following cookbooks inside the cookbooks repository:

  • apt: instructions on how to use apt
  • ubuntu: this one manages the sources and executes apt-get update
  • build-essential: installs the build-essential package
  • git: installs git
  • perl: configures CPAN
  • runit: will be used to monitor redis and our web application

Edit vagrant_main/recipes/default.rb to add them:

require_recipe "ubuntu"
require_recipe "git"
require_recipe "perl"
require_recipe "redis"
require_recipe "runit"

If the VM is already started, you can run vagrant provision or vagrant up. This will deploy the previous cookbooks on the VM. When it's done, you can log on the VM with vagrant ssh.

You'll need to additional recipes: one for redis; one for presque. You'll find them on my GitHub account. Copy the two recipes inside your cookbook directory, and execute vagrant provision to install them.

If everything works fine, you should be able to start using presque. Test this:

% curl http://localhost:8080/q/foo/
{"error":"no job"}

% curl -X POST -H "Content-Type: application/json" -d '{"foo":"bar"}' http://localhost:8080/q/foo/

% curl http://localhost:8080/q/foo/
{"foo":"bar"}

If everything is fine, you can shut down the VM with vagrant halt.

Mounting directories

Instead of pulling from github, you may prefer to mount a local directory on the VM. For this, you'll need to modifiy the Vagrantfile to add this:

config.vm.share_folder "v-code", "/deployment/code", "~/code/perl5"
config.vm.share_folder "v-data", "/deployment/data", "~/code/data"

This will mount your local directories perl5 and data under /deployment/{code,data} on the VM. So now you can edit your files locally and they will be automagically updated on the VM at once.

and now the awesome part

If you're like me, you may end up with the need to have multiple VMs which will talk to each other. Common scenarios are a VM with the website, and another one with the DB, or one VM with a bunch of API webservices and another with Workers who need to interact with the VM. Rejoice, this kind of stuff is also handled by vagrant!

Replace the content of the previous Vagrantfile with this:

Vagrant::Config.run do |config|
  config.vm.box = "base"
  config.vm.provisioner = :chef_solo

  config.chef.cookbooks_path = "cookbooks"

  config.vm.define :presque do |presque_config|
    presque_config.chef.add_recipe("vagrant_presque")
    presque_config.vm.network("192.168.1.10")
    presque_config.vm.forward_port("presque", 80, 8080)
    presque_config.vm.customize do |vm|
      vm.name = "vm_presque"
    end
  end

  config.vm.define :workers do |workers_config|
    workers_config.chef.add_recipe("vagrant_workers")
    workers_config.vm.network("192.168.1.11")
    workers_config.vm.customize do |vm|
      vm.name = "vm_workers"
    end
  end
end

In this configuration, we're creating two VMs, presque and workers. You'll need to create two new cookbooks, one for each new VM (vagrant_presque, with the same content as vagrant_main, and vagrant_workers, with only the recipe for ubuntu and the instructions to install curl). Once it's done, boot the two VMs:

% vagrant up presque
% vagrant up workers

Now let's log on the worker VM

% vagrant ssh workers
vagrant@vagrantup:~$ curl http://192.168.1.10:5000/q/foo
{"error":"no job"}

and voilà.

Conclusion

I've started to use vagrant for all my new personal projects and for most of my stuff at work. I really enjoy using this, as it's easy to create a cookbook or add one, it's easy to setup a multi VM environment, you can share a configuration amongst your coworkers, etc.

If you haven't started yet using a VM for your own projects, you really should give it a try, or use a simple VirtualBox setup. If you want to read more on the subject, these two blog posts may be relevant:

(oh, and BTW, did you notice that Dancer 1.2 is out ?)