Working With Vagrant

14 Feb 2019 in Big_data / Big Data on Vagrant

This note will provide you some background on how to deploy virtual machines with Vagrant. More specifically, we will have a look at the basic outline and features of Vagrantfile . This tutorial is a distilled version of the official Vagrant Documentation, and most of the examples are borrowed from there.

We will do the following:

• Spin up a generic Ubuntu VM
• Install apache server
• Perform port forwarding
• Learn how to create a multi-machine environment
• Connect multiple virtual machines with VPN

Install Vagrant

Download and install VirtualBox from https://www.virtualbox.org/wiki/Downloads Download and install Vagrant from http://downloads.vagrantup.com

Vagrant uses VirtualBox as a standard hypervisor. At least one hypervisor provider required to run a VM.

Optional: Setting up Vagrant project with a local box image

Download Box images

• i386
• amd64

Use downloaded images to init your VM.

vagrant init my-box /path/to/my-box.box

Setup up a Vagrant project from a repository:

Go to https://app.vagrantup.com/boxes/search and select an image that you are going to spin up. We recommend choosingubuntu/trusty64. You will see that you can configure your VM using only a single command

vagrant init ubuntu/trusty64

Create a where you want to store your VM and run configuration.

Creating a VM

Your VM is ready, and you can now ask Vagrant to start up a VM as configured by the default Vagrantfile:

  vagrant up 

The VM is now running in Virtualbox. You can ssh into it (no password required) as follows:

  vagrant ssh # ssh into the VM

Further, you can log out by typing exit or pressing Ctrl+D. Even though you closed your ssh session, the VM is still working in the background. You can verify this by opening VirtualBox window.

To terminate or suspend your VM you can type vagrant halt or vagrant suspend correspondingly. If you want to delete the instantiation of this VM configuration, type vagrant destroy.

Synced Directory

Note that on the new VM, /vagrant is a shared directory linked with the init directory on your host machine. On your host machine try

echo "Hello World" > hello_world.txt

Then log into your VM and verify the presence of the file

vagrant ssh
vagrant@vagrant-ubuntu-trusty-64:~$ cd /vagrant/
vagrant@vagrant-ubuntu-trusty-64:/vagrant$ ls
hello_world.txt  Vagrantfile
vagrant@vagrant-ubuntu-trusty-64:/vagrant$ cat hello_world.txt 
Hello World
vagrant@vagrant-ubuntu-trusty-64:/vagrant$ 

Vagrantfile

The configuration of your VM is done with Vagrantfile. When you were setting up your VM, this file was automatically added to your directory. Take a look at the content. There are several useful configs:

1. config.vm.box specifies the name of your VM
2. config.vm.provider specifies your hypervisor and additional related settings. The default hypervisor is VirtualBox
3. config.vm.network defines network settings for your host to see your VM
4. config.vn.synced_folder allows to change default shared folder path
5. config.vm.provision specifies additional configuration

Synced Directory

To change the default shared directory path, simply modify the Vagrantfile

Vagrant.configure("2") do |config|
  # other config here

  config.vm.synced_folder "src/", "/srv/website"
end

Provisioning

Provision section of the Vagrantfile allows you to install additional software on your VM during its deployment. Let us create a simple example. In your init directory create bootstrap.sh with the following content

#!/usr/bin/env bash

apt-get update
apt-get install -y apache2
if ! [ -L /var/www ]; then
  rm -rf /var/www
  ln -fs /vagrant /var/www
fi

As you can see, it installs apache2 from the repository and swaps /vagrant for its server directory. To execute this script during deployment, modify Vagrantfile

Vagrant.configure("2") do |config|
  config.vm.box = "my-box"
  config.vm.provision :shell, path: "bootstrap.sh"
end

Provisioning happens at certain points during the lifetime of your Vagrant environment:

• On the first vagrant up that creates the environment, provisioning is run. If the environment was already created and the up is just resuming a machine or booting it up, they will not run unless the --provision flag is explicitly provided.
• When vagrant provision is used on a running environment.
• When vagrant reload --provision is called. The --provision flag must be present to force provisioning.

You can also bring up your environment and explicitly not run provisioners by specifying --no-provision.

Networking

Vagrant allows to set up port forwarding to your VM. This will enable you to access a port on your machine, but actually, have all the network traffic forwarded to a specific port on the guest machine. Modify Vagrantfile according to the following

Vagrant.configure("2") do |config|
  config.vm.box = "my-box"
  config.vm.provision :shell, path: "bootstrap.sh"
  config.vm.network :forwarded_port, guest: 80, host: 4567
end

You need to perform vagrant reload after changing networking settings.

Since you modified the default server directory, you need to create a directory html in your shared folder, containing a simple html file index.html.

Hello World!

Once the machine is running again, load http://127.0.0.1:4567 in your browser. You should see a web page that is being served from the virtual machine that was automatically setup by Vagrant.

Multi-Machine

Vagrant can define and control multiple guest machines per Vagrantfile. This is known as a “multi-machine” environment.

These machines are generally able to work together or are somehow associated with each other. Here are some use-cases people are using multi-machine environments for today:

• Accurately modeling a multi-server production topology, such as separating a web and database server.
• Modeling a distributed system and how they interact with each other.
• Testing an interface, such as an API to a service component.
• Disaster-case testing: machines dying, network partitions, slow networks, inconsistent world views, etc.

One of the simplest ways to create a multi-machine environment is

BOX_URL = "/path/to/image"

Vagrant.configure("2") do |config|
  config.vm.define "master" do |subconfig|
    subconfig.vm.box = "my-box1"
    subconfig.vm.box_url = BOX_URL
  end

  config.vm.define "node1" do |subconfig|
    subconfig.vm.box = "my-box2"
    subconfig.vm.box_url = BOX_URL
  end

  config.vm.define "node2" do |subconfig|
    subconfig.vm.box = "my-box3"
    subconfig.vm.box_url = BOX_URL
  end
end

To ssh into any of these, you will need to type ssh command with a name

vagrant ssh my-box1

To destroy all VMs, type

vagrant destroy -f

Multi-Machine Networking

To allow machines to communicate with each other, specify additional networking parameters. First, each VM needs a unique hostname. By default, each of the VMs has the same hostname (vagrant). Change this with

subconfig.vm.hostname = "a.host.name"

Next, we need a way of getting the IP address for a hostname. For this, we’ll use DNS – or mDNS to be more precise.

On Ubuntu, mDNS is provided by Avahi. To install Avahi on each node, we’ll use Vagrant’s provisioning feature.

Before the last end in the Vagrantfile, we’ll add this code block:

config.vm.provision "shell", inline: <<-SHELL
  apt-get install -y avahi-daemon libnss-mdns
SHELL

This will call apt-get install -y avahi-daemon libnss-mdns on every VM.

Last, we need to connect the VMs through a private network.

For each VM, we need to add a config like this (where each VM will have a different IP address):

subconfig.vm.network :private_network, ip: "10.0.0.10"

You can now call vagrant up and then ssh into any of the VMs:

vagrant ssh my-box1

From there you can ping any other VM by using their hostname (plus .local at the end):

ping VM_addr.local

Multiple Provisioners

Multiple config.vm.provision methods can be used to define multiple provisioners. These provisioners will be run in the order they’re defined. This is useful for a variety of reasons, but most commonly it is used so that a shell script can bootstrap some of the systems so that another provisioner can take over later.

Additional Features

For the information about additional features visit documentation web site

• Push
• Plugins
• Providers
• Triggers
• Other

Troubleshooting

• If Vagrant does not see VirtualBox even though you have installed it, try downgrading to VirtualBox 5.1