What does Puppet generally use to pull in configuration from external resources?

Puppet primarily utilizes resources to pull in configuration from external sources. Resources are fundamental building blocks in Puppet that define the desired state of system components, such as files, packages, or services. They specify how these components should be configured, allowing Puppet to manage their state based on the configurations defined in your Puppet code.

When configuration is needed from external sources, such as files on remote servers or data from databases, resources are often employed to declare those dependencies and ensure correct fetching and configuration—whether they're pulling data from an external file, an API, or another data source.

Classes, nodes, and manifests are key components of Puppet's architecture, but they serve different purposes. Classes group related resources and provide a way to organize configurations. Nodes are specific machines or devices to which these configurations are applied. Manifests are files written in Puppet's declarative language that define resources, classes, and their relationships. While they play a critical role in the configuration process, the specific action of pulling in external configuration data is carried out through resources.