Architecture

Pulp can be viewed as consisting of two parts, the platform (which includes both the server and client applications) and plugins (which provide support for a particular set of content types).

Platform

The Pulp application is a platform into which support for particular types of content is installed. The Pulp Platform refers to the following major components:

  • Server - The server-side application includes all of the infrastructure for handling repositories, consumers, and users. This includes the plumbing for handling functionality related to these pieces, such as synchronizing a repository or sending an install request to a consumer. The actual behavior of how those methods function, however, is dependent on the plugin fielding the request.
  • Client - The platform includes both the admin and consumer clients. These clients contain type-agnostic commands, such as logging in or handling events. Each client can be enhanced with type-specific commands through the use of extensions.
  • Agent - The agent runs on each consumer and is used to field requests sent from the Pulp server to that consumer. Similar to the client, the platform provides the agent and relies on the use of handlers to provide support for a particular content type.

Plugins

Support for handling specific content types, such as RPMs or Puppet Modules, is provided through plugins into each of the three major platform components.

Note

The term plugin is typically used to refer just to the server-side plugins. Collectively, the set of server, client, and agent plugins for a particular set of content types are usually referred to as a “support bundle.”

  • Plugin - The server-side components that handle either downloading and inventorying content in Pulp (called an importer) or publishing content in a repository (referred to as a distributor).
  • Extension - The components plugged into either the admin or consumer command line clients to provide new commands in the client for type-specific operations.
  • Handler - The agent-side components that are used to field invocations from the server to a consumer, such as binding to a repository or installing content.

Git Repositories

Pulp’s code is stored on GitHub. The Pulp organization’s GitHub repositories are divided into two types:

  • The Pulp repository is used for all platform code, including the server, clients, and agent. There should be no code in here that caters to a specific content type. Put another way, all plugins to the platform components are located outside of this repository.
  • Each type support bundle (RPM, Puppet, etc.) is in its own repository. Each of these repositories contains their own setup.py and RPM spec files, as well as any other configuration files needed to support the plugins (for example, httpd configuration files).