Puppet Best Practices

Chapter 7. Roles and Profiles

Roles and profiles is a best-practice design pattern for Puppet that provides an interface between your business logic and reusable Puppet modules. Profiles are reusable groups of modules that configure applications. Roles utilize one or more profiles to implement business- or site-specific requirements. When implemented properly, this design pattern greatly simplifies node classification in large, diverse organizations.

Note

Roles and profiles were not a feature provided by Puppet; they are a design pattern originally described in Craig Dunn’s blog post, “Designing Puppet–Roles and Profiles”. It described an evolution of Puppet usage that became a community standard and recognized best practice.

Back in Chapter 1, we discussed how the single responsibility principle enables creation of reusable building blocks for modular design. Those principles help create great modules, but reusable modules need to be combined together to deploy a complete service or application. A functional service often consists of different software components, each of which already has modules designed to configure it. A profile is the larger building block that encapsulates a specific build of that service.

Without using roles and profiles, a node would receive a list of classes from either a node statement or an ENC. This has some significant limitations:

• An ENC can provide only classes and parameters: it cannot declare resources or defined types.

• An ENC cannot declare ...