我正在安装 Bundle
thulehoang@thulehoang-X455LAB:~/workspace/hello_app$ bundle install，但是它不起作用。
这是错误：
Gem::InstallError: rack requires Ruby version >= 2.2.2.
An error occurred while installing rack (2.0.3), and Bundler cannot continue.
Make sure that gem install rack -v '2.0.3' succeeds before bundling.