Gemfile says:
gem \'sqlite3\', :groups => [:development, :test]
gem \'mysql2\', :group => :production
yet when I type bundle instal
The point of Bundler is to create a consistent gem environment across deployments. Gems, unfortunately, can interact even if they aren't loaded or required. So for maximum consistency, all gems should be installed, even if they aren't all required.
However, if you don't want all gems installed all the time, you can use the bundle install --without option.