For scripts to help you find projects running 1.0, generate a draft 2.0 config.yml file, and to get started with migration, see the CircleCI 2.0 Migration documentation which has a complete list of tools with links and descriptions.
Do you need the latest version of Bundler?
CircleCI typically tracks the latest stable version of bundler.
Your project may occasionally need to use a pre-release version, which is easy to add to your build.
Just add the following to your circle.yml file.