Puppet Module Design
A Puppet module packages reusable configuration policy for one technology or responsibility. Good module design gives users a small typed public interface while hiding implementation classes, data, templates, files, tests, and platform-specific decisions behind it.
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Don't Panic
Don't Panic - Puppet Module Design
Puppet Module Design is the subject of this course. A Puppet module is a reusable policy package. It manages one technology or responsibility and gives other code a stable way to declare that policy.
The useful unit of work is a closed loop: clarify the goal and boundaries, gather the inputs the practice requires, make the decision or change, record evidence, and return with owners for the next cycle. Skipping any link leaves teams busy without durable results.
Tooling supports the loop; it does not replace it. Choose tools after the boundary and evidence model are clear. Comparing products without that model produces feature matrices that do not change how the work runs.
Common failure modes include undefined ownership, metrics that count activity instead of outcomes, and irreversible steps taken without a review path. Treat those as design defects in the practice, not as individual heroics to compensate later.
Operators should be able to explain which signals would change a decision this week. If no signal can change the plan, the practice has become ritual. Keep the feedback path short enough that evidence still influences the next cycle.
Name the owners for each stage of the loop before the work scales. Unowned stages become permanent exceptions. Record decisions with enough context that a future operator can tell why a tradeoff was accepted. Prefer fewer, sharper metrics that change behavior over broad dashboards that only describe activity after the fact.
Read the Intro for the core model. Use the Cheatsheet when you need the operating map. Updates tracks official guidance when this course configures an update source; otherwise the practice is settled without a live feed.
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Sources
- https://help.puppet.com/core/current/Content/PuppetCore/modules_fundamentals.htm
Supports
- Modules as reusable building blocks for one task or technology
- Modulepath loading and supported content types
- https://help.puppet.com/core/current/Content/PuppetCore/style_guide_modules.htm
Supports
- Module structure, metadata, documentation, examples, dependencies, testing, and semantic versioning
- https://help.puppet.com/core/current/Content/PuppetCore/style_guide_classes.htm
Supports
- Typed parameters, public and private classes, defaults, and relationships
- Hiera module data instead of params inheritance
- Opt-in and selective exported resources
- https://help.puppet.com/core/current/Content/PuppetCore/configuring_roles_and_profiles.htm
Supports
- Component, profile, and role layers
- Site-specific composition through profiles and one role classification
- https://help.puppet.com/core/current/Content/PuppetCore/adding_hiera_data_module.htm
Supports
- Namespaced Hiera defaults packaged with modules
- Replacement of params classes with data in modules
- https://help.puppet.com/core/current/Content/PuppetCore/puppet_lookup.htm
Supports
- Global, environment, and module Hiera layers
- First-found and merge behavior
- https://help.puppet.com/core/current/Content/PuppetCore/modules_metadata.htm
Supports
- Required metadata fields and compatibility information
- Semantic versions and bounded dependency ranges
- Operating-system and Puppet requirements
- https://help.puppet.com/pdk/current/topics/create_a_module.htm
Supports
- PDK module skeleton and metadata creation
- https://help.puppet.com/pdk/current/topics/pdk_testing.htm
Supports
- Metadata, syntax, Puppet style, Ruby style, and unit-test tooling
- Testing against maintained Puppet and PE versions
- https://help.puppet.com/pdk/current/topics/unit_testing_modules.htm
Supports
- Catalog compilation and expected-resource unit tests
- Unit-test limits for real managed-system behavior
- https://help.puppet.com/core/current/Content/PuppetCore/bgtm.htm
Supports
- RSpec Puppet, Puppet spec helper, Litmus, documentation, and semantic-release practices
- https://help.puppet.com/core/current/Content/PuppetCore/lang_containment.htm
Supports
- Relationships between containers and contained resources
- https://github.com/awesome-puppet-org/awesome-puppet
Supports
- Selection and descriptions of Puppet VS Code Extension, Vox Pupuli, PuppetModule.info, and Puppet Cookbook
