Vagrant

It's quite good

What is it?

From the Vagrant site:

"Create and configure lightweight, reproducible, and portable development environments."

What does that mean?

Helps you run an app in a virtual machine and manage it with ease

Do what with virtual machines now?

• Create and destroy, quickly and safely
• Speedy start, suspend and stop operations
• Automagic forwarding of ports (eg. ssh and http)
• Repeatable provisioning and configuration

Terminology

Host and Guest

Host: your actual, physical machine

Guest: a virtual machine running on your host

Terminology

Base box

• A lightweight, pre-prepared OS image
• Usually Linux; could be Windows or something else
• Base boxes are stashed for reuse by Vagrant in ~/.vagrant.d/

How does Vagrant work?

• Downloads the base box (if not already present)
• Clones the base box to your project
• Boots the base box
• Runs config and provisioning instructions

Project files

• They still live on your physical machine
• But the VM can see them, via shared folders...
• ...so you can use your usual editor and tools

Running the app

• Your Ruby, Python, Node or whatever app runs in the VM
• HTTP ports can be forwarded from guest to host...
• ... so browsers running on the host can see the site

Get going

• Install stuff
• Create a Vagrantfile
• Make a provision script

Install stuff

NB: VMware also supported (more stable, not free)

Create a Vagrantfile

Just a config file. Have a basic one created for you:

vagrant init precise64 http://files.vagrantup.com/precise64.box

Or make your own

Should specify:

• base box name
• base box URL
• networking
• provisioning info

A simple Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant.configure("2") do |config|
  config.vm.box = "precise64"
  config.vm.box_url = "http://files.vagrantup.com/precise64.box"
  config.vm.network :forwarded_port, host: 4567, guest: 4567
  config.vm.provision :shell, :path => "provision.sh"
end

Provisioning

Works with:

• Chef
• Puppet
• Shell scripts
• SaltStack (soon, Python fans)

Chef and Puppet are hard

Let's use shell scripts

A simple provision.sh

#!/usr/bin/env bash

# Update system package lists
sudo apt-get update

# Install necessary system packages
sudo apt-get install -y \ # automatic yes to prompts with -y
build-essential \
nodejs \

# Install Bundler (no docs)
gem install --no-rdoc --no-ri \
bundler \

# Bundle all the gems in the gemfile
cd /vagrant/www
bundle install

vagrant up

All done.

Now:

$ vagrant up

vagrant up

$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
[default] Importing base box 'precise64'...
[default] Matching MAC address for NAT networking...
[default] Setting the name of the VM...
[default] Clearing any previously set forwarded ports...
[default] Creating shared folders metadata...
[default] Clearing any previously set network interfaces...
[default] Preparing network interfaces based on configuration...
[default] Forwarding ports...
[default] -- 22 => 2222 (adapter 1)
[default] -- 4567 => 4567 (adapter 1)
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] VM booted and ready for use!
[default] Configuring and enabling network interfaces...
[default] Mounting shared folders...
[default] -- /vagrant
[default] Running provisioner: shell...
[default] Running: /var/folders/2j/lkj6zqjx3hd6wzwsz2v55bmw0000gn/T/vagrant-shell20130612-1787-14r3iia
#  a few minutes + lots of install logging

What now?

Common commands:

• vagrant up
• vagrant ssh
• vagrant suspend
• vagrant halt
• vagrant reload
• vagrant destroy

vagrant up

First use also runs provisioning and starts the VM

After that, it just starts the VM

vagrant ssh

Get in and muck about

$ vagrant ssh
Welcome to Ubuntu 12.04 LTS (GNU/Linux 3.2.0-23-generic x86_64)

 * Documentation:  https://help.ubuntu.com/
Welcome to your Vagrant-built virtual machine.
Last login: Fri Sep 14 06:23:18 2012 from 10.0.2.2
vagrant@precise64:/vagrant$ pwd
/vagrant
vagrant@precise64:/vagrant$ exit
logout
Connection to 127.0.0.1 closed.

vagrant suspend

Pause the VM

• Keeping the state
• Freeing up resources

$ vagrant suspend
[default] Saving VM state and suspending execution...

vagrant halt

Shut down the VM

• Lose state
• Keep installed packages etc.

$ vagrant halt
[default] Discarding saved state of VM...

vagrant destroy

Destroy the VM

Doesn't affect your project files or the base box.

$ vagrant destroy
Are you sure you want to destroy the 'default' VM? [y/N] y
[default] Forcing shutdown of VM...
[default] Destroying VM and associated drives...

vagrant reload

Like vagrant up, but runs the provision script again.

The same as running vagrant up for the first time.

Why bother?

If you can run an app on your actual, physical machine, why bother running them in a Vagrant VM?

Consistent environment for all

Put the Vagrantfile and provision script under version control.

All team members can run the same stack on the same (virtual) OS.

Consistent environment for all

No more:

• Spending ages trying to get dependencies sorted so work can start
• Weird issues caused by slightly different versions
• "It works fine on my machine" conversations
• Windows-using tech clients getting upset

Less thought

If you are:

• Using a different machine
• Coming back to a project a few months later
• Helping a new team member get going

Less thought

$ git clone https://github.com/user/project-name.git project-name
$ cd project-name
$ cat README.md
$ vagrant up

Done (pretty much)

Code beats documentation

Documentation is good; code is better.

Written instructions on how to get an app running can get out of date quickly.

Code beats documentation

• Script the provisioning
• Quickly becomes clear when dependencies are broken
• Easy to fix, then distribute

Fallback

You're not forced into using Vagrant: you can still install the dependencies on your host machine and run the app there, if you like.

Resources

• Vagrant docs: start here
• Vagrant book: just released
• Vagrant AWS plugin: manage EC2 and VPC instances
• Vagrantbox.es: lots of base boxes
• Rove: Chef and Vagrantfile build tool
• Puphet: Puppet and Vagrantfile for PHP build tool
• fabtools: handy helpers for Fabric (see Vagrant API)

STFU Paul

Fanks

Presented at HMTL, 12th June 2013

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