Bundle install gets killed

Hello,

I have been following this tutorial on how to get started with Ruby on Rails:

https://www.digitalocean.com/community/tutorials/how-to-use-the-ruby-on-rails-one-click-application-on-digitalocean

But got stuck when running bundle install, the install gets killed halfway…

root@X:/home/rails/sample_tasks# bundle install
Don't run Bundler as root. Bundler can ask for sudo if it is needed, and installing your bundle as root will break this application for all non-root users on this machine.
Fetching gem metadata from https://rubygems.org/...........
Fetching version metadata from https://rubygems.org/...
Fetching dependency metadata from https://rubygems.org/..
Resolving dependencies...
Using rake 10.4.2
Using i18n 0.7.0
Using json 1.8.3
Using minitest 5.8.0
Using thread_safe 0.3.5
Using tzinfo 1.2.2
Using activesupport 4.2.1
Using builder 3.2.2
Using erubis 2.7.0
Using mini_portile 0.6.2
Killed

Any ideas on how to resolve?