How to use external (for bundler) util gem with rake tasks of rails project

Question

I'm trying to integrate backup gem (github.com/backup/backup) at rails project. Backup gem is not recommended for using in Gemfile, so I'm trying to install it by capistrano task. And I make task in lib/rasks/backup.rake path, contained something like:

namespace :backup do
  desc "Perfom Backup"
  task :perform do
    %x{ backup perform -t beam_bank -c config/Backup/config.rb }
  end
end

But executing that task cause error:

micron-l% rake backup:perform
/home/space/.gem/ruby/2.2.0/gems/bundler-1.10.6/lib/bundler/rubygems_integration.rb:292:in `block in replace_gem': backup is not part of the bundle. Add it to Gemfile. (Gem::LoadError)
    from /home/space/.gem/ruby/2.2.0/bin/backup:22:in `<main>'

Adding "gem 'backup', require: false" to Gemfile cause some dependency conflict. So we decide the using Gemfile is not apropriate in our current case.

I would be very thankful for ideas to solve this problem... Thanks in advance..

Answer 1

The answer is:

Use bundler helper for run script in clean environment. In this case it can be done something like this:

Bundler.clean_system('backup perform -t beam_bank -c config/Backup/config.rb')

The reference to docs on this problem: http://bundler.io/v1.10/man/bundle-exec.1.html#Shelling-out