Problem: Publications are not needed for Docker plugin

Solution: Add 'repository_version' field to DockerDistribution

This patch allows users to create DockerDistributions that serve repository versions. A distribution can
be created with either a repository or repository version defined. If a repository is defined, the latest
version of that repository is always available at the distribution. If a repository version is specified,
then that repository version is always available at that distribution.

This patch updates an existing test and adds a new one. The two tests assert that a docker or podman pull
can be performed when a repository is used in a distribution and when a repository version is used.

This patch also fixes the tests to work with docker as the client.

closes: #4669
https://pulp.plan.io/issues/4669

README.rst

@@ -178,24 +178,16 @@ Look at the new Repository Version created
     }
 
 
-Publish a Repository Version and create a Publication
------------------------------------------------------
+Add a Docker Distribution to serve the latest Repository Version
+----------------------------------------------------------------
 
-``$ http POST :24817/pulp/api/v3/docker/publish/ repository=$REPO_HREF``
-
-.. code:: json
-
-    {
-        "task": "/pulp/api/v3/tasks/fd4cbecd-6c6a-4197-9cbe-4e45b0516309/"
-    }
-
-``$ export PUBLICATION_HREF=$(http :24817/pulp/api/v3/publications/ | jq -r '.results[0] | ._href')``
-
-Add a Docker Distribution to serve your publication
----------------------------------------------------
-
-``$ http POST http://localhost:24817/pulp/api/v3/docker-distributions/ name='baz' base_path='foo' publication=$PUBLICATION_HREF``
+The Docker Distribution will serve the latest version of a Repository if the repository is
+specified during creation/update of a Docker Distribution. The Docker Distribution will serve
+a specific repository version if repository_version is provided when creating a Docker
+Distribution. Either repository or repository_version can be set on a Docker Distribution, but not
+both.
 
+``$ http POST http://localhost:24817/pulp/api/v3/docker-distributions/ name='baz' base_path='foo' repository=$REPO_HREF``
 
 .. code:: json
 

pulp_docker/app/models.py

@@ -4,7 +4,7 @@
 from django.db import models
 
 from pulpcore.plugin.download import DownloaderFactory
-from pulpcore.plugin.models import BaseDistribution, Content, Remote
+from pulpcore.plugin.models import BaseDistribution, Content, Remote, RepositoryVersion
 
 from . import downloaders
 
@@ -287,5 +287,18 @@ class DockerDistribution(BaseDistribution):
     A docker distribution defines how a publication is distributed by Pulp's webserver.
     """
 
+    repository_version = models.ForeignKey(RepositoryVersion, null=True, on_delete=models.CASCADE)
+
     class Meta:
         default_related_name = 'docker_distributions'
+
+    def get_repository_version(self):
+        """
+        Returns the repository version that is supposed to be served by this DockerDistribution.
+        """
+        if self.repository:
+            return RepositoryVersion.latest(self.repository)
+        elif self.repository_version:
+            return self.repository_version
+        else:
+            return None

pulp_docker/app/registry.py

@@ -122,7 +122,8 @@ async def tags_list(request):
         path = request.match_info['path']
         distribution = await Registry.match_distribution(path)
         tags = {'name': path, 'tags': set()}
-        for c in distribution.publication.repository_version.content:
+        repository_version = distribution.get_repository_version()
+        for c in repository_version.content:
             c = c.cast()
             if isinstance(c, ManifestTag) or isinstance(c, ManifestListTag):
                 tags['tags'].add(c.name)
@@ -149,11 +150,12 @@ async def get_tag(request):
         path = request.match_info['path']
         tag_name = request.match_info['tag_name']
         distribution = await Registry.match_distribution(path)
+        repository_version = distribution.get_repository_version()
         accepted_media_types = await Registry.get_accepted_media_types(request)
         if MEDIA_TYPE.MANIFEST_LIST in accepted_media_types:
             try:
                 tag = ManifestListTag.objects.get(
-                    pk__in=distribution.publication.repository_version.content,
+                    pk__in=repository_version.content,
                     name=tag_name
                 )
             # If there is no manifest list tag, try again with manifest tag.
@@ -166,7 +168,7 @@ async def get_tag(request):
         if MEDIA_TYPE.MANIFEST_V2 in accepted_media_types:
             try:
                 tag = ManifestTag.objects.get(
-                    pk__in=distribution.publication.repository_version.content,
+                    pk__in=repository_version.content,
                     name=tag_name
                 )
             except ObjectDoesNotExist:
@@ -211,11 +213,11 @@ async def get_by_digest(request):
         path = request.match_info['path']
         digest = "sha256:{digest}".format(digest=request.match_info['digest'])
         distribution = await Registry.match_distribution(path)
+        repository_version = distribution.get_repository_version()
         log.info(digest)
         try:
-            ca = ContentArtifact.objects.get(
-                content__in=distribution.publication.repository_version.content,
-                relative_path=digest)
+            ca = ContentArtifact.objects.get(content__in=repository_version.content,
+                                             relative_path=digest)
             headers = {'Content-Type': ca.content.cast().media_type}
         except ObjectDoesNotExist:
             raise PathNotResolved(path)

pulp_docker/app/serializers.py

@@ -10,6 +10,7 @@
     BaseDistributionSerializer,
     DetailRelatedField,
     IdentityField,
+    NestedRelatedField,
     RemoteSerializer,
     SingleArtifactContentSerializer,
 )
@@ -182,8 +183,7 @@ class DockerDistributionSerializer(BaseDistributionSerializer):
         view_name='docker-distributions-detail'
     )
     base_path = serializers.CharField(
-        help_text=_('The base (relative) path component of the published url. Avoid paths that \
-                    overlap with other distribution base paths (e.g. "foo" and "foo/bar")'),
+        help_text=_('The base (relative) path that identifies the registry path.'),
         validators=[validators.MaxLengthValidator(
             models.DockerDistribution._meta.get_field('base_path').max_length,
             message=_('Distribution base_path length must be less than {} characters').format(
@@ -197,7 +197,68 @@ class DockerDistributionSerializer(BaseDistributionSerializer):
         help_text=_('The Registry hostame:port/name/ to use with docker pull command defined by '
                     'this distribution.')
     )
+    repository_version = NestedRelatedField(
+        help_text=_('A URI of the repository version to be served by the Docker Distribution.'),
+        required=False,
+        label=_('Repository Version'),
+        queryset=models.RepositoryVersion.objects.all(),
+        view_name='versions-detail',
+        lookup_field='number',
+        parent_lookup_kwargs={'repository_pk': 'repository__pk'},
+    )
+
+    def validate(self, data):
+        """
+        Validate the parameters for creating or updating Docker Distribution.
+
+        This method makes sure that only repository or a repository version is associated with a
+        Docker Distribution. It also validates that the base_path is a relative path.
+
+        Args:
+            data (dict): Dictionary of parameter value to validate
+
+        Returns:
+            Dict of validated data
+
+        Raises:
+            ValidationError if any of the validations fail.
+
+        """
+        super().validate(data)
+        if 'repository' in data:
+            repository = data['repository']
+        elif self.instance:
+            repository = self.instance.repository
+        else:
+            repository = None
+
+        if 'repository_version' in data:
+            repository_version = data['repository_version']
+        elif self.instance:
+            repository_version = self.instance.repository_version
+        else:
+            repository_version = None
+
+        if repository and repository_version:
+            raise serializers.ValidationError({'repository': _("Repository can't be set if "
+                                                               "repository_version is set also.")})
+        if 'publication' in data and data['publication']:
+            raise serializers.ValidationError({'publication': _("DockerDistributions don't serve "
+                                                                "publications. A repository or "
+                                                                "repository version should be "
+                                                                "specified.")})
+        if 'publisher' in data and data['publisher']:
+            raise serializers.ValidationError({'publication': _("DockerDistributions don't work "
+                                                                "with publishers. A repository or "
+                                                                "a repository version should be "
+                                                                "specified.")})
+        if 'base_path' in data and data['base_path']:
+            self._validate_relative_path(data['base_path'])
+
+        return data
 
     class Meta:
         model = models.DockerDistribution
-        fields = BaseDistributionSerializer.Meta.fields + ('base_path', 'registry_path')
+        fields = BaseDistributionSerializer.Meta.fields + ('base_path',
+                                                           'registry_path',
+                                                           'repository_version')

pulp_docker/app/tasks/__init__.py

@@ -1,3 +1,2 @@
 from .distribution import create, delete, update  # noqa
-from .publishing import publish  # noqa
 from .synchronize import synchronize  # noqa

pulp_docker/app/viewsets.py

@@ -10,11 +10,9 @@
 
 from pulpcore.plugin.serializers import (
     AsyncOperationResponseSerializer,
-    RepositoryPublishURLSerializer,
     RepositorySyncURLSerializer,
 )
 
-from pulpcore.plugin.models import RepositoryVersion, Publication
 from pulpcore.plugin.tasking import enqueue_with_reservation
 from pulpcore.plugin.viewsets import (
     ContentViewSet,
@@ -149,44 +147,6 @@ def sync(self, request, pk):
         return OperationPostponedResponse(result, request)
 
 
-class DockerPublicationViewSet(NamedModelViewSet, mixins.CreateModelMixin):
-    """
-    A ViewSet for Docker Publication.
-    """
-
-    endpoint_name = 'docker/publish'
-    queryset = Publication.objects.all()
-    serializer_class = RepositoryPublishURLSerializer
-
-    @swagger_auto_schema(
-        operation_description="Trigger an asynchronous task to create a docker publication",
-        responses={202: AsyncOperationResponseSerializer}
-    )
-    def create(self, request):
-        """
-        Queues a task that publishes a new Docker Publication.
-
-        """
-        serializer = RepositoryPublishURLSerializer(
-            data=request.data,
-            context={'request': request}
-        )
-        serializer.is_valid(raise_exception=True)
-        repository_version = serializer.validated_data.get('repository_version')
-
-        # Safe because version OR repository is enforced by serializer.
-        if not repository_version:
-            repository = serializer.validated_data.get('repository')
-            repository_version = RepositoryVersion.latest(repository)
-
-        result = enqueue_with_reservation(
-            tasks.publish,
-            [repository_version.repository],
-            kwargs={'repository_version_pk': str(repository_version.pk)}
-        )
-        return OperationPostponedResponse(result, request)
-
-
 class DockerDistributionViewSet(NamedModelViewSet,
                                 mixins.UpdateModelMixin,
                                 mixins.RetrieveModelMixin,