The CodeKeeper measures metrics especially about complexity and size of Ruby files, aiming to be a Ruby version of gmetrics

Mesuring metrics leads to keep codebase simple and clean, and I name the gem CodeKeeper.

Now CodeKeeper supports the cyclomatic complexity of a file, the ABC software metric of a file, and class length. The scores are output to stdout of a json or csv format.


Add this line to your application's Gemfile:

gem 'code_keeper'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install code_keeper


Run CodeKeeper and you get scores of metrics from stdout like

$ bundle exec code_keeper app/models/user.rb app/models/admin.rb > metrics.json
$ cat metrics.json

If you need a csv format, change the configuration as explained later.

Run CodeKeeper

To measure metrics of all the ruby files recursively in the current directory, run

$ bundle exec code_keeper ./

You can specify a single file or multiple files.

$ bundle exec code_keeper ./dir/a.rb ./dir/b.rb

CodeKeeper makes you configure the following way:

CodeKeeper.configure do |config|
  # If you choose metrics, specify as follows:
  config.metrics = %i(cyclomatic_complexity abc_metric class_length)
  # The number of threads. The default is 2. Executed sequentially if you set 1.
  config.number_of_threads = 4
  # The default is json
  config.format = :json


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the CodeKeeper project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.