The document outlines best practices and recommendations for modern Puppet module development, including the importance of using the Puppet Forge and checking modules for compatibility, maintenance, and functionality. It emphasizes the need for thorough testing, including unit and acceptance tests, to ensure module reliability. Additionally, it encourages community involvement and documentation to enhance the Puppet ecosystem.

1. Modern Module
Development
Morgan Haskel | Puppet Labs
@KnittyNerd

2. Definitions
• ‘Module’ - code to install and configure a single
piece of software
• ‘Roles and Profiles’ - code to compose modules
in a more site-specific manner

3. How Did We Get Here?
• Before the forge
• Early forge
• Today

4. What Now?
• Deploying a new
technology != writing
a new module
• Start with the Puppet
Forge
• Check GitHub

5. Module Evaluation

6. Supported Modules
• Extensively tested
• Platform compatibility
• Widely used
• Actively maintained

7. Approved Modules
• Nominated by module authors or community
members
• Nominations reviewed by modules team
• Checked for functionality and following best
practices
• Evaluated against comparable modules
• Nominate a module you love today!

8. Module Scoring System
• Lint checking
• Puppet compatibility
• Metadata checking
• Community ratings

9. Does It Work For You?
• Check the module
documentation
• See if the module can
generate your
existing configuration
• How customizable is
it?

10. Other Checks
• Is the module actively maintained?
• Are issues and pull requests responded to?
• Can the module get you close to your
configuration?
• Does the module follow best practices?

11. Starting From Scratch

12. Write The Module You Want
• Writing generic
modules is hard
• Iterative development
helps
• You don’t have to do
it alone

13. Scoping, Scoping, Scoping
• Only manage a single
thing
• Avoid monolithic
modules
• Tighter scope ==
greater flexibility

14. Checking Your Work
• Unit and acceptance
tests for all new
modules
• Unit tests for most
new features
• Acceptance tests for
new big features

15. • Lower overhead
• Verify against catalog
• Test for compilation
• Exercise parameters
• More overhead
• Verify against running
system
• Full path test of software
• Check for config
correctness
Unit Tests
Acceptance
Tests

16. Danger Zone
Do not run acceptance
tests anywhere but on a
test system or virtual
machine.
Acceptance tests
occasionally have bugs
that can be very
destructive (rm -rf /)

17. Upkeep
• Test new code and
updates to existing code
• Regression tests are
important

18. Documentation
• Especially important
with shared code
• Don’t forget in code
comments

19. Life After Release
Module work isn’t done yet.

20. puppet-community
• GitHub organization
• Modules and tooling
maintained by and for the
Puppet community
• Reach out to @daenney and
@hirojin if you need more
information!

21. Development Toolkit
• Brand New Puppet Language Style Guide
• Consistency with ModuleSync
• #puppet-dev on freenode

22. Roles and Profiles

23. Putting It All Together
When in doubt, add
additional layers of
abstraction.

24. • Each node has a
single role
• Each role is
composed of one or
many profiles
• Each profile is
composed of other
profiles or modules

25. An Example

28. Improving the Ecosystem
Find and get involved in
a local Puppet User
Group!

29. Links!
• Nominate approved: https://tickets.puppetlabs.com/browse/
MODULES/component/12141
• Style Guide: https://docs.puppetlabs.com/guides/
style_guide.html
• ModuleSync: https://github.com/puppetlabs/modulesync
• puppet-community: http://puppet-community.github.io/
• Roles and Profiles: http://www.craigdunn.org/2012/05/239/
• Puppet User Group: http://puppetlabs.com/community/PUG

30. Questions?