Container Support

Create the Tag model.

Tag(Content):

• name CharField(255)
• manifest ForeignKey(Manifest, null=True, related_name='tags', on_delete=CASCADE)
• manifest_list ForeignKey(ManifestList, null=True, related_name='tags', on_delete=CASCADE)

unique_together = (name, manifest)
unique_together = (name, manifest_list)

Design assumptions:

• Pre-save validation on the model ensures that one-of but not both manifest and manifest_list are set.
• Tag name uniqueness and referential integrity{1} will be enforced by the plugin. During sync, this happens in the task logic. For content add/remove API calls, this happens in the (docker specific) view. Both can re-use the same code.

[1] Tag referential integrity is ensuring that when a manifest or manifest_list is removed from a repository, referencing tags are also removed. Also, when a tag is added to a repository, referenced manifest or manifest_list are also added.