Plugin Roles

This documents available plugin roles.

1. list of plugin roles

   Role	Class	Status
   Metadata	Metadata	done
   Connector	Connector	done
   Probing	Probing	done
   Structure	Structure	done
   Structure Val	StructureValidator	done
   Generator	Generator	done
   Goals Val	GoalValidator	done
   Statistics	Statistics	done
   Pull Source	PullSource	done
   Pull Target	PullTarget	done
   Version	Version	done
   Decision	Decision	done
   Remote	Remote	none
   Syncing	Syncing	none

2. Plugin Capabilities

   • Metadata
     • Initial metadata construction
     • Connector data accumulation
     • ClientMetadata instance delivery
     • Introspection interface (for bcfg2-info & co)
   • Connector
     • Provide additional data for ClientMetadata instances
   • Probing
     • send executable probes to clients and receive data responses
   • Structure
     • Produce a list of configuration entries that should be included in client configurations
     • Each structure plugin is produces a list of structures
     • Core verifies that each bundle listed has been constructed
   • Structure Validation
     • Validate a client entry list’s internal consistency, modifying if needed
   • Generator
   • Goals Validation
     • Validate client goals, modifying if needed
   • Pull Source
     • Plugin can provide entry information about clients
   • Pull Target
     • Plugin can accept entry data and merge it into the specification
   • Version
     • Plugin can read revision information from VCS of choice
     • Will provide an interface for producing commits made by the bcfg2-server
   • Decision

3. Configuration of plugins

   Plugin configuration will be simplified substantially. Now, a single list of plugins (including plugins of all capabilities) is specified upon startup (either via bcfg2.conf or equivalent). This mechanism replaces the current split configuration mechanism where generators, structures, and other plugins are listed independently. Instead, all plugins included in the startup list will be initialized, and each will be enabled in all roles that it supports. This will remove a current source of confusion and potential configuration errors, wherein a plugin is enabled for an improper set of goals. (ie Cfg enabled as a structure, etc) This does remove the possibility of partially enabling a plugin for one of its roles without activating it across the board, but I think this is a corner case, which will be poorly supported by plugin implementers. If needed, this use case can be explicitly supported by the plugin author, through use of a config file directive.

4. User Visible Changes

   Connector data is added to ClientMetadata instances using the name of the connector plugin. This means that the dictionary of key/val probe pairs included with metadata is now available as metadata.Probes (instead of metadata.probes). Once properties are available the same way, they will likewise change names to metadata.Properties from their current name.

   Plugin configuration will change. A single field “plugins” in bcfg2.conf will supercede the combination of the “generators” and “structures” fields.

   Default loading of needed plugins is now explicit; this means that Statistics (if used) should be listed in the plugins line of bcfg2.conf.

5. Notes

   • Need to ensure bundle accumulation occurs with connector groups