Vagrant

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What is Vagrant?

Vagrant is an important tool for software development: it provides reproducible environments in which to develop, test, and run software.

How it works

Vagrant uses a file call Vagrantfile in the local directory to control the installation and configuration of machines. Upon execution of the vagrant up command, Vagrant initializes a virtual machine based on the provided box, applies any specified provisioning, and configures SSH for access.

As an example, consider the following Vagrantfile which is part of the cloudmesh repository.

# IMPORTANT
#
# In order for this configuration to properly work you need to set
# environmental variables:
#
# - PORTALNAME: your username on FutureSystems
# - PROJECTID: the project you are associated with
##
# Make sure that ssh-agent is running properly in order to access
# futuresystems.
# $ eval `ssh-agent`
# $ ssh-add ~/.ssh/id_rsa
# $ echo $SSH_AGENT_PID # check that this is set
#
# Example usage:
# $ export PORTALNAME=albert
# $ export PROJECTID=fg101
# $ eval `ssh-agent`
# $ ssh-add ~/.ssh/id_rsa
# $ vagrant up

PORTALNAME = ENV['PORTALNAME']
PROJECTID  = ENV['PROJECTID']

$script = <<SCRIPT

set -o xtrace  # trace commands
set -o errexit # stop if something fails

# parameters for install, configure, start scripts
export portalname=#{PORTALNAME}
export projectid=#{PROJECTID}
export venv=$HOME/ENV

# install system deps and cloudmesh
curl -s https://raw.githubusercontent.com/cloudmesh/get/master/cloudmesh/ubuntu/14.04.sh | bash

# make sure to activate virtualenv
source $venv/bin/activate

# configure
curl -s https://raw.githubusercontent.com/cloudmesh/get/master/cloudmesh/configure.sh | bash

# start
curl -s https://raw.githubusercontent.com/cloudmesh/get/master/cloudmesh/start.sh | bash

# update bashrc
echo "" >>~/.bashrc
echo "source $venv/bin/activate" >>~/.bashrc

SCRIPT

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(2) do |config|
  config.vm.box = "ubuntu/trusty64"
  config.vm.box_check_update = true
  config.vm.network "private_network", ip: "192.168.33.10"
  config.vm.provision "shell", privileged: false, inline: $script

  # Forward ssh-agent so that `cm-iu fetch` will work without needing
  # to copy the ssh keypair onto the VM
  # In order for this to work you need to:
  # $ eval `ssh-agent`
  # $ ssh-add ~/.ssh_id
  config.ssh.forward_agent = true;

end

Let us look at what it does. Comments begin with the # symbol and are for documentation purposes only. In this case, the instructions tell us the setup that needs to be done before running vagrant up.

Next, the environmental variables PORTALNAME and PROJECTID are retrieved and injected into a provisioning shell script defined and stored in the $script.

The rest of the file is fairly straightforward:

  • use the ubuntu/trusty64 box as the base system to run
  • we want to make sure that the most up-to-date box is used so we enable automatic update checks
  • the machine should not be accessible from the network (though it does have network access) to we set the IP address in a private network.
  • the provisioning shell script is specified and will run as an unprivileged user
  • finally, use the ssh-agent forwarding system. This way the ssh keypairs for futuresystems access do not need to be copied into from the host machine into the workstation.

At this point running vagrant up will download the ubuntu/trusty64 box if it is not already present, boot the machine, and execute the provisioning script. The user can then run vagrant ssh to log into the machine and run any desired tests.

Boxes

We have seen the use of the Ubuntu 14.04 (ubuntu/trusty64) box as a base image for Vagrant to use. Many other options for boxes are publicly available.

Provisioners

Additionally, there are other options for provisioning the machines managed by Vagrant. In addition to shell, Ansible and many others are supported (see the provisioning index)

Providers

By default, Vagrant uses VirtualBox to manage machines. Other options are available such as VMWare or Docker. Additionally, the design of Vagrant’s software architecture allows plugins to be built to support alternative custom providers. For instance, plugins for Amazon Web Services, as well as OpenStack are available to install.