A working workaround to run rvmsudo in Capistrano 3.

capistrano3-rvmsudo.md

1. Edit /etc/sudoers

https://rvm.io/integration/sudo

2. Custom execute command

# deploy.rb
  desc "Export Upstart script"
  task :export_upstart do
    on roles(:app) do
      execute [
        "cd #{release_path} &&",
        'export rvmsudo_secure_path=0 && ',
        "#{fetch(:rvm_path)}/bin/rvm #{fetch(:rvm_ruby_version)} do",
        'rvmsudo',
        'bundle exec foreman export -a glkickstart -u ubuntu -p 8787 upstart /etc/init'
      ].join(' ')
    end
  end
  after 'deploy:updated', 'deploy:export_upstart'

You saved the day. Thanks :)