Puppet 8 readiness with Onceover

Puppet 8 has been released, with it comes security enhancements, the dropping of deprecated features, and performance improvements, you can read more about Puppet 8 on this blog post.

In this blog post, well look at how you can take your existing Puppet 7 code and use Onceover, a free testing tool, to test it against Puppet 8 to prepare for your migration.

Puppet 8

Of the many changes to Puppet 8, a few will have a direct impact on your current Puppet code.
Strict mode will now be enforced, for example, in Puppet 7 you could add a string to an integer, "1" + 1, this will now fail.
Legacy facts, which have been deprecated for some time, have been removed.
Hiera 3 has also been removed.

Onceover

The simple question we want to answer is "will my Puppet 7 code compile into a catalog on Puppet 8" and for that, Onceover is the perfect tool. If you haven't used Onceover before, it's a stand alone tool that you can run on any machine, and test that the roles and profiles in your control-repo will compile into catalogs.

Install Ruby 3

The first thing we'll need to do is install Ruby 3, it's a requirement of Puppet 8. Follow these steps to install it Installing Ruby.

If you're on your own workstation you may want to consider using rbenv to allow you to quickly switch between versions of Ruby that your other project may depend upon.

Install Onceover

The first step in installing Onceover is to clone your control-repo onto your system.

Then install bundler gem install bundler; this is required to read the Gemfile we'll produce in the next step to install the required Gems.

In the root of your control-repo create a Gemfile, this specifies the main Gems we want to install and their versions. If you wanted to use a different version of Puppet, just change the version in the Gemfile. If you host Gems internally such as Artifactory, you can specify the source in here too.

# Gemfile
source "https://rubygems.org"
gem 'puppet', '~> 8.4'
gem 'onceover', '~> 3.22'

Run bundle install to install all the gems and their dependencies.

Run bundle exec onceover init to initialise the control-repo, one of the things this does is create the .onceover directory and puts the Onceover config file, onceover.yaml, into the spec directory.

Run a test

To keep things simple, my control-repo contains one role.

# site-modules/role/manifests/example.pp
class role::example {
  include profile::coercion.pp
}

And that role will contain one profile, this profile contains some code that would compile a catalog under Puppet 7, but not under Puppet 8.

# site-modules/profile/manifests/coercion.pp
class profile::coercion {
  $result = '1' + 1
}

The last job is to modify the Onceover configutation file, to keep this simple I just want it to compile the example role on Ubuntu 20.04.

classes:
  - role::example

nodes:
  - Ubuntu-20.04-64

node_groups:
  non_windows_nodes:
    - Ubuntu-20.04-64

test_matrix:
  - all_nodes:
      classes: 'all_classes'
      tests: 'spec'

Finaly, to run the test, run onceover run spec.
This will return the following error, which is expected, as Puppet 8 enforces strict mode on coercion.

role::example: F

role::example: failed
  errors:
    Evaluation Error: The string '1' was automatically coerced to the numerical value 1
      file: site-modules/profile/manifests/coercion.pp
      line: 3
      column: 13
      factsets: Ubuntu-20.04-64

Refactor our code and rerun the test

The error is reasonably clear, we provided a string and it was used as an integer. Lets fix that code!

# site-modules/profile/manifests/coercion.pp
class profile::coercion {
  $result = 1 + 1
}

The result is a pass!

role::example: P

Conclusion

Using Onceover and the Puppet 8 Gem, we can quickly detect code that will not work on Puppet 8 and we can do this on a test machine or laptop, well away from our Puppet servers and production environment.

A note on Continuous Delivery for Puppet Enterprise (CD4PE)

If you're using Continuous Delivery you're probably already using Onceover on the puppet-dev-tools:4.x container that ships with Continuous Delivery. To start testing against Puppet 8, duplicate the Onceover job you're already running, but change the Docker container it uses to puppet-dev-tools:puppet8