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Contributing to Puppet modules

So you want to contribute to a Puppet module: Great! Below are some instructions to get you started doing that very thing while setting expectations around code quality as well as a few tips for making the process as easy as possible.

Table of Contents

  1. Getting Started
  2. Commit Checklist
  3. Submission
  4. More about commits
  5. Testing
  6. Get Help

Getting Started

  • Fork the module repository on GitHub and clone to your workspace

  • Make your changes!

Commit Checklist

The Basics

  • my commit is a single logical unit of work

  • I have checked for unnecessary whitespace with "git diff --check"

  • my commit does not include commented out code or unneeded files

The Content

  • my commit includes tests for the bug I fixed or feature I added

  • my commit includes appropriate documentation changes if it is introducing a new feature or changing existing functionality

  • my code passes existing test suites

The Commit Message

  • the first line of my commit message includes:

    • an issue number (if applicable), e.g. "(MODULES-xxxx) This is the first line"

    • a short description (50 characters is the soft limit, excluding ticket number(s))

  • the body of my commit message:

    • is meaningful

    • uses the imperative, present tense: "change", not "changed" or "changes"

    • includes motivation for the change, and contrasts its implementation with the previous behavior



Push and PR

  • Push your changes to your fork

  • Open a Pull Request against the repository in the puppetlabs organization

More about commits

  1. Make separate commits for logically separate changes.

    Please break your commits down into logically consistent units which include new or changed tests relevant to the rest of the change. The goal of doing this is to make the diff easier to read for whoever is reviewing your code. In general, the easier your diff is to read, the more likely someone will be happy to review it and get it into the code base.

    If you are going to refactor a piece of code, please do so as a separate commit from your feature or bug fix changes.

    We also really appreciate changes that include tests to make sure the bug is not re-introduced, and that the feature is not accidentally broken.

    Describe the technical detail of the change(s). If your description starts to get too long, that is a good sign that you probably need to split up your commit into more finely grained pieces.

    Commits which plainly describe the things which help reviewers check the patch and future developers understand the code are much more likely to be merged in with a minimum of bike-shedding or requested changes. Ideally, the commit message would include information, and be in a form suitable for inclusion in the release notes for the version of Puppet that includes them.

    Please also check that you are not introducing any trailing whitespace or other "whitespace errors". You can do this by running "git diff --check" on your changes before you commit.

  2. Sending your patches

    To submit your changes via a GitHub pull request, we highly recommend that you have them on a topic branch, instead of directly on "master". It makes things much easier to keep track of, especially if you decide to work on another thing before your first change is merged in.

    GitHub has some pretty good general documentation on using their site. They also have documentation on creating pull requests.

    In general, after pushing your topic branch up to your repository on GitHub, you can switch to the branch in the GitHub UI and click "Pull Request" towards the top of the page in order to open a pull request.

  3. Update the related JIRA issue.

    If there is a JIRA issue associated with the change you submitted, then you should update the ticket to include the location of your branch, along with any other commentary you may wish to make.


Getting Started

Our Puppet modules provide Gemfiles, which can tell a Ruby package manager such as bundler what Ruby packages, or Gems, are required to build, develop, and test this software.

Please make sure you have bundler installed on your system, and then use it to install all dependencies needed for this project in the project root by running

% bundle install --path .bundle/gems
Fetching gem metadata from
Fetching gem metadata from
Using rake (10.1.0)
Using builder (3.2.2)
-- 8><-- many more --><8 --
Using rspec-system-puppet (2.2.0)
Using serverspec (0.6.3)
Using rspec-system-serverspec (1.0.0)
Using bundler (1.3.5)
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.

NOTE: some systems may require you to run this command with sudo.

If you already have those gems installed, make sure they are up-to-date:

% bundle update

Running Tests

With all dependencies in place and up-to-date, run the tests:

Unit Tests

% bundle exec rake spec

This executes all the rspec tests in the directories defined here and so on. rspec tests may have the same kind of dependencies as the module they are testing. Although the module defines these dependencies in its metadata.json, rspec tests define them in .fixtures.yml.

Acceptance Tests

Some Puppet modules also come with acceptance tests, which use beaker. These tests spin up a virtual machine under VirtualBox, controlled with Vagrant, to simulate scripted test scenarios. In order to run these, you need both Virtualbox and Vagrant installed on your system.

Run the tests by issuing the following command

% bundle exec rake spec_clean
% bundle exec rspec spec/acceptance

This will now download a pre-fabricated image configured in the default node-set, install Puppet, copy this module, and install its dependencies per spec/spec_helper_acceptance.rb and then run all the tests under spec/acceptance.

Writing Tests

Unit Tests

When writing unit tests for Puppet, rspec-puppet is your best friend. It provides tons of helper methods for testing your manifests against a catalog (e.g. contain_file, contain_package, with_params, etc). It would be ridiculous to try and top rspec-puppet's documentation but here's a tiny sample:

Sample manifest:

file { "a test file":
  ensure => present,
  path   => "/etc/sample",

Sample test:

it 'does a thing' do
  expect(subject).to contain_file("a test file").with({:path => "/etc/sample"})

Acceptance Tests

Writing acceptance tests for Puppet involves beaker and its cousin beaker-rspec. A common pattern for acceptance tests is to create a test manifest, apply it twice to check for idempotency or errors, then run expectations.

it 'does an end-to-end thing' do
  pp = <<-EOF
    file { 'a test file': 
      ensure  => present,
      path    => "/etc/sample",
      content => "test string",
  apply_manifest(pp, :catch_failures => true)
  apply_manifest(pp, :catch_changes => true)

describe file("/etc/sample") do
  it { contain "test string" }

If you have commit access to the repository

Even if you have commit access to the repository, you still need to go through the process above, and have someone else review and merge in your changes. The rule is that all changes must be reviewed by a project developer that did not write the code to ensure that all changes go through a code review process.

The record of someone performing the merge is the record that they performed the code review. Again, this should be someone other than the author of the topic branch.

Get Help

On the web

On chat

  • Slack ( #forge-modules, #puppet-dev, #windows, #voxpupuli
  • IRC (freenode) #puppet-dev, #voxpupuli