How To Install Ruby on Rails on Ubuntu 14.04 using RVM

Introduction

Ruby on Rails is one of the most popular application stacks for developers wishing to create sites and web apps. The Ruby programming language, coupled with the Rails development framework, makes app development simple.

Since Ruby on Rails doesn't come in a neatly packaged format, getting the framework installed used to be one of the more difficult parts of getting started. Luckily, tools like rvm, the Ruby Version Manager, have made installation simple.

In this guide, we'll show how to install rvm on an Ubuntu 14.04 VPS, and use it to install a stable version of Ruby and Rails. Although you can go through these procedures as the root user, we'll assume you're operating using an unprivileged user as shown in steps 1-4 in this guide.

The Quick Way

The quickest way of installing Ruby on Rails with rvm is to run the following commands as a regular user:

gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
\curl -sSL https://get.rvm.io | bash -s stable --rails

You will be prompted for your regular user's password as part of the installation procedure.

Let's go over exactly what's happening here.

The gpg command contacts a public key server and requests a key associated with the given ID. In this case we are requesting the RVM project's key which is used to sign each RVM release. Having the RVM project's public key allows us to verify the legitimacy of the RVM release we will be downloading, which is signed with the matching private key.

The \curl portion uses the curl web grabbing utility to grab a script file from the rvm website. The backslash that leads the command ensures that we are using the regular curl command and not any altered, aliased version.

The -s flag indicates that the utility should operate in silent mode, the -S flag overrides some of this to allow curl to output errors if it fails. The -L flag tells the utility to follow redirects.

The script is then piped directly to bash for processing. The -s flag indicates that the input is coming from standard in. We then specify that we want the latest stable version of rvm, and that we also want to install the latest stable Rails version, which will pull in the associated Ruby.

Following a long installation procedure, all you need to do is source the rvm scripts by typing:

source ~/.rvm/scripts/rvm

You should now have a full Ruby on Rails environment configured.

Installing Specific Ruby and Rails Versions

If you need to install specific versions of Ruby for your application, you can do so with rvm like this:

rvm install ruby_version

After the installation, we can list the available Ruby versions we have installed by typing:

rvm list

We can switch between the Ruby versions by typing:

rvm use ruby_version

We can use various Rails versions with each Ruby by creating gemsets and then installing Rails within those using the normal gem commands:

rvm gemset create gemset_name    # create a gemset
rvm ruby_version@gemset_name  # specify Ruby version and our new gemset
gem install rails -v rails_version   # install specific Rails version

The gemsets allow us to have self-contained environments for gems and allow us to have multiple environments for each version of Ruby that we install.