Execute remote task with Capistrano 3

gistfile1.rb

# Usage: bundle exec cap staging execute:rake task=db:migrate
namespace :execute do
  task :rake do
    on roles(:all) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, "exec rake #{ENV['task']}"
        end
      end
    end
  end
end