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A Virtual Machine for Ruby on Rails Core Development


Please note this VM is not designed for Rails application development, only Rails core development.

This project automates the setup of a development environment for working on Ruby on Rails itself. Use this virtual machine to work on a pull request with everything ready to hack and run the test suites.


  • VirtualBox

  • Vagrant 2

  • Install the vagrant-vbguest plugin: vagrant plugin install vagrant-vbguest.

How To Build The Virtual Machine

Building the virtual machine is this easy:

host $ git clone
host $ cd rails-dev-box
host $ vagrant up

That's it.

After the installation has finished, you can access the virtual machine with

host $ vagrant ssh
Welcome to Ubuntu 22.04 LTS (GNU/Linux 5.15.0-25-generic x86_64)

Port 3000 in the host computer is forwarded to port 3000 in the virtual machine. Thus, applications running in the virtual machine can be accessed via localhost:3000 in the host computer. Be sure the web server is bound to the IP, instead of, so it can access all interfaces:

bin/rails server -b

RAM and CPUs

By default, the VM launches with 2 GB of RAM and 2 CPUs.

These can be overridden by setting the environment variables RAILS_DEV_BOX_RAM and RAILS_DEV_BOX_CPUS, respectively. Settings on VM creation don't matter, the environment variables are checked each time the VM boots.

RAILS_DEV_BOX_RAM has to be expressed in megabytes, so configure 4096 if you want the VM to have 4 GB of RAM.

What's In The Box

  • Development tools

  • Git

  • Ruby 3.0

  • Bundler

  • SQLite3, MySQL, and Postgres

  • Databases and users needed to run the Active Record test suite

  • System dependencies for nokogiri, sqlite3, mysql2, and pg

  • Memcached

  • Redis

  • RabbitMQ

  • An ExecJS runtime

Recommended Workflow

The recommended workflow is

  • edit in the host computer and

  • test within the virtual machine.

Just clone your Rails fork into the rails-dev-box directory on the host computer:

host $ ls MIT-LICENSE Vagrantfile
host $ git clone<your username>/rails.git

Vagrant mounts that directory as /vagrant within the virtual machine:

vagrant@rails-dev-box:~$ ls /vagrant MIT-LICENSE rails Vagrantfile

Install gem dependencies in there:

vagrant@rails-dev-box:~$ cd /vagrant/rails
vagrant@rails-dev-box:/vagrant/rails$ bundle

We are ready to go to edit in the host, and test in the virtual machine.

Please have a look at the Contributing to Ruby on Rails guide for tips on how to run test suites, how to generate an application that uses your local checkout of Rails, etc.

This workflow is convenient because in the host computer you normally have your editor of choice fine-tuned, Git configured, and SSH keys in place.

Virtual Machine Management

When done just log out with ^D and suspend the virtual machine

host $ vagrant suspend

then, resume to hack again

host $ vagrant resume


host $ vagrant halt

to shutdown the virtual machine, and

host $ vagrant up

to boot it again.

You can find out the state of a virtual machine anytime by invoking

host $ vagrant status

Finally, to completely wipe the virtual machine from the disk destroying all its contents:

host $ vagrant destroy # DANGER: all is gone

Please check the Vagrant documentation for more information on Vagrant.

Faster Rails test suites

The default mechanism for sharing folders is convenient and works out the box in all Vagrant versions, but there are a couple of alternatives that are more performant.


Vagrant 1.5 implements a sharing mechanism based on rsync that dramatically improves read/write because files are actually stored in the guest. Just throw

config.vm.synced_folder '.', '/vagrant', type: 'rsync'

to the Vagrantfile and either rsync manually with

vagrant rsync

or run

vagrant rsync-auto

for automatic syncs. See the post linked above for details.


If you're using Mac OS X or Linux you can increase the speed of Rails test suites with Vagrant's NFS synced folders.

With an NFS server installed (already installed on Mac OS X), add the following to the Vagrantfile:

config.vm.synced_folder '.', '/vagrant', type: 'nfs' 'private_network', ip: '' # ensure this is available


host $ vagrant up

Please check the Vagrant documentation on NFS synced folders for more information.


On vagrant up, it's possible to get this error message:

The box 'ubuntu/yakkety64' could not be found or
could not be accessed in the remote catalog. If this is a private
box on HashiCorp's Atlas, please verify you're logged in via
vagrant login. Also, please double-check the name. The expanded
URL and error message are shown below:

URL: [""]

And a known work-around (Varying-Vagrant-Vagrants/VVV#354) can be:

sudo rm /opt/vagrant/embedded/bin/curl


Released under the MIT License, Copyright (c) 2012–ω Xavier Noria.


A virtual machine for Ruby on Rails core development







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