Raise If Root is a small gem that helps prevent your application from ever running as the root user (uid 0).

Many software systems rely on user privilege separation for security reasons. Especially within containers or chroots, running as a non-privileged user gives stronger isolation.

Raise If Root helps enforce that you never inadvertently load your application code as root.

Will it protect you if your attacker is already running as root? Probably not. But it does help remove opportunities for error, where you might accidentally run root rake tasks, cron jobs, or deploy scripts.

Add the gem to your application's Gemfile:

gem 'raise-if-root', '~> 0'

Require it from your main application code:

require 'raise-if-root'

There is no step three! This will raise RaiseIfRoot::AssertionFailed if the current uid is 0.

See the YARD documentation.

If you want to enforce that the application is running as a particular user, there are several more specific functions available.

Load the library, which doesn't immediately raise when you load it.

# load the library, which doesn't raise
require 'raise-if-root/library'

# raise if running as uid 1000
RaiseIfRoot.raise_if_uid(1000)

# raise unless user is nobody
RaiseIfRoot.raise_if(username_not: 'nobody')

# raise with multiple conditions
RaiseIfRoot.raise_if(uid_not: 1000, gid_not: 500)

If you want to sound the alarm with something more than just the exception, you can add callbacks to send emails, smoke signals, etc.

# load the library, which doesn't raise
require 'raise-if-root/library'

RaiseIfRoot.add_assertion_callback do |err|
  Mail.deliver do
    from    '[email protected]'
    to      '[email protected]'
    subject 'App was run as root'
    body    "RaiseIfRoot is raising an exception:\n  #{err.inspect}\n"
  end
end

# ensure we're not root
RaiseIfRoot.raise_if_root

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request