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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 stages-concept-docs 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 ~pulpcore.plugin.models.RepositoryContent and saving it.
  • Remove ~pulpcore.plugin.models.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 ~pulpcore.plugin.models.ContentArtifact to be able to create relations with the artifact models.
    • instance of ~pulpcore.plugin.models.RemoteArtifact to store information about artifact from remote source and to make a relation with ~pulpcore.plugin.models.ContentArtifact created before.
  • If a remote content should be downloaded right away (aka immediate download policy), use the suggested downloading <download-docs> 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 ~pulpcore.plugin.models .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 ~pulpcore.plugin.models.ContentArtifact with a reference to the created ~pulpcore.plugin.models.Artifact.
    • create and save an instance of the ~pulpcore.plugin.models.RepositoryContent to associate the content to a repository.
    • save all created artifacts and content: ExampleContent, ~pulpcore.plugin.models.ContentArtifact, ~pulpcore.plugin.models.RemoteArtifact.
  • Use ~pulpcore.plugin.models.ProgressBar to report the progress of some steps if needed.