warden_hooks.rb

Warden::Manager.after_set_user do |user, auth, opts|
    auth.cookies.signed["user.id"] = user.id
    auth.cookies.signed["user.expires_at"] = 30.minutes.from_now
end

Warden::Manager.before_logout do |user, auth, opts|
    auth.cookies.signed["user.id"] = nil
    auth.cookies.signed["user.expires_at"] = nil
end