Allow same tag to be created for multiple revisions

This PS fixes a unique constraint for revision tags, allowing a
tag to be associated with only one revision. It also adds an
additional try/catch block when attempting to update an existing
revision (although it is mostly superfluous).

Closes 14

Change-Id: I83cfacb25f71a33641054c5a26e5b9a1c9907658

deckhand/control/revision_tags.py

@@ -44,7 +44,7 @@ class RevisionTagsResource(api_base.BaseResource):
 
         try:
             resp_tag = db_api.revision_tag_create(revision_id, tag, tag_data)
-        except errors.RevisionNotFound as e:
+        except (errors.RevisionNotFound, errors.RevisionTagNotFound) as e:
             raise falcon.HTTPNotFound(description=e.format_message())
         except errors.RevisionTagBadFormat as e:
             raise falcon.HTTPBadRequest(description=e.format_message())

deckhand/db/sqlalchemy/api.py

@@ -840,9 +840,14 @@ def revision_tag_create(revision_id, tag, data=None, session=None):
         resp = tag_model.to_dict()
     except db_exception.DBDuplicateEntry:
         # Update the revision tag if it already exists.
-        tag_to_update = session.query(models.RevisionTag)\
-            .filter_by(tag=tag, revision_id=revision_id)\
-            .one()
+        LOG.debug('Tag %s already exists for revision_id %s. Attempting to '
+                  'update the entry.', tag, revision_id)
+        try:
+            tag_to_update = session.query(models.RevisionTag)\
+                .filter_by(tag=tag, revision_id=revision_id)\
+                .one()
+        except sa_orm.exc.NoResultFound:
+            raise errors.RevisionTagNotFound(tag=tag, revision=revision_id)
         tag_to_update.update({'data': data})
         tag_to_update.save(session=session)
         resp = tag_to_update.to_dict()

deckhand/db/sqlalchemy/models.py

@@ -110,17 +110,15 @@ class Revision(BASE, DeckhandBase):
 
 
 class RevisionTag(BASE, DeckhandBase):
-    UNIQUE_CONSTRAINTS = ('tag', 'revision_id')
     __tablename__ = 'revision_tags'
 
-    tag = Column(String(64), primary_key=True, nullable=False)
+    id = Column(Integer, primary_key=True)
+    tag = Column(String(64), nullable=False)
     data = Column(oslo_types.JsonEncodedDict(), nullable=True, default={})
     revision_id = Column(
         Integer, ForeignKey('revisions.id', ondelete='CASCADE'),
         nullable=False)
 
-    UniqueConstraint(*UNIQUE_CONSTRAINTS)
-
 
 class Document(BASE, DeckhandBase):
     UNIQUE_CONSTRAINTS = ('schema', 'name', 'revision_id')

deckhand/tests/unit/control/test_revision_tags_controller.py

@@ -24,8 +24,10 @@ class TestRevisionTagsController(test_base.BaseControllerTest):
         super(TestRevisionTagsController, self).setUp()
         rules = {'deckhand:create_cleartext_documents': '@'}
         self.policy.set_rules(rules)
+        self.revision_id = self._create_revision()
 
-        # Create a revision to tag.
+    def _create_revision(self):
+        # Create a revision with any document (doesn't matter).
         secrets_factory = factories.DocumentSecretFactory()
         payload = [secrets_factory.gen_test('Certificate', 'cleartext')]
         resp = self.app.simulate_put(
@@ -33,8 +35,9 @@ class TestRevisionTagsController(test_base.BaseControllerTest):
             headers={'Content-Type': 'application/x-yaml'},
             body=yaml.safe_dump_all(payload))
         self.assertEqual(200, resp.status_code)
-        self.revision_id = list(yaml.safe_load_all(resp.text))[0]['status'][
+        revision_id = list(yaml.safe_load_all(resp.text))[0]['status'][
             'revision']
+        return revision_id
 
     def test_delete_tag(self):
         rules = {'deckhand:create_tag': '@',
@@ -57,6 +60,22 @@ class TestRevisionTagsController(test_base.BaseControllerTest):
             headers={'Content-Type': 'application/x-yaml'})
         self.assertEqual(404, resp.status_code)
 
+    def test_apply_same_tag_to_different_revisions(self):
+        rules = {'deckhand:create_cleartext_documents': '@',
+                 'deckhand:create_tag': '@'}
+        self.policy.set_rules(rules)
+
+        # self.revision_id already created in setUp.
+        alt_revision_id = self._create_revision()
+        tag = 'same_tag'
+
+        # Apply the same tag to both revisions.
+        for revision_id in (self.revision_id, alt_revision_id):
+            resp = self.app.simulate_post(
+                '/api/v1.0/revisions/%s/tags/%s' % (revision_id, tag),
+                headers={'Content-Type': 'application/x-yaml'})
+            self.assertEqual(201, resp.status_code)
+
 
 class TestRevisionTagsControllerNegativeRBAC(test_base.BaseControllerTest):
     """Test suite for validating negative RBAC scenarios for revision tags