Adding and Removing Content

For adding and removing content, Pulp 3 provides a layered plugin API. The docs below explain our lower level API; this information is helpful to understand how a synchronize task works under the hood.

Repository Versions

Starting with Pulp 3, repositories are versioned. A new immutable respository version is created when its set of content units changes

To facilitate the creation of repository versions a pulpcore.plugin.models.RepositoryVersion context manager is provided. Plugin Writers are strongly encouraged to use RepositoryVersion as a context manager to provide transactional safety, working directory setup, and database cleanup after encountering failures.

with RepositoryVersion.create(repository) as new_version:

   # add content manually
   new_version.add_content(content)
   new_version.remove_content(content)

Warning

Any action that adds/removes content to a repository must create a new RepositoryVersion. Every action that creates a new RepositoryVersion must be asynchronous (defined as a task). Task reservations are necessary to prevent race conditions.

Synchronizing

Tip

Please consider using the high level Synchronizing Repositories with the async-Pipeline for actual implementations.

Most plugins will define a synchronize task, which fetches content from a remote repository, and adds it to a Pulp repository.

A typical synchronization task will follow this pattern:

  • Download and analyze repository metadata from a remote source.
  • Decide what needs to be added to repository or removed from it.
  • Associate already existing content to a repository by creating an instance of RepositoryContent and saving it.
  • Remove RepositoryContent objects which were identified for removal.
  • For every content which should be added to Pulp create but do not save yet:
    • instance of ExampleContent which will be later associated to a repository.
    • instance of ContentArtifact to be able to create relations with the artifact models.
    • instance of RemoteArtifact to store information about artifact from remote source and to make a relation with ContentArtifact created before.
  • If a remote content should be downloaded right away (aka immediate download policy), use the suggested downloading solution. If content should be downloaded later (aka on_demand or background download policy), feel free to skip this step.
  • Save all artifact and content data in one transaction:
    • in case of downloaded content, create an instance of Artifact. Set the file field to the absolute path of the downloaded file. Pulp will move the file into place when the Artifact is saved. The Artifact refers to a downloaded file on a filesystem and contains calculated checksums for it.
    • in case of downloaded content, update the ContentArtifact with a reference to the created Artifact.
    • create and save an instance of the RepositoryContent to associate the content to a repository.
    • save all created artifacts and content: ExampleContent, ContentArtifact, RemoteArtifact.
  • Use ProgressReport to report the progress of some steps if needed.