fix: Address small issues with revision rollback controller

1. There is no exception called `InvalidRollback` in Deckhand (it
was removed a while back). Instead, the only exception that
db_api.revision_rollback raises is RevisionNotFound from
the revision_get call internally.

So catch that instead from the controller.

2. The default value of parameters is `str` so when revision_id
of '0' is passed to the db module for processing, it skips over
the check for `if revision_id == 0` as revision_id is a str,
not int. So this leverages builtin int converter logic in
falcon [0] but requires uplifting the version of falcon to
at least 1.3.0 to make use of it [1].

[0] https://falcon.readthedocs.io/en/stable/api/routing.html#field-converters
[1] https://falcon.readthedocs.io/en/1.3.0/api/routing.html#field-converters

Change-Id: I068cd9e9b6818a5d51501f2718ee2d40d556c094

deckhand/control/rollback.py

@@ -47,7 +47,7 @@ class RollbackResource(api_base.BaseResource):
         try:
             rollback_revision = db_api.revision_rollback(
                 revision_id, latest_revision)
-        except errors.InvalidRollback as e:
+        except errors.RevisionNotFound as e:
             with excutils.save_and_reraise_exception():
                 LOG.exception(e.format_message())
 

deckhand/service.py

@@ -64,7 +64,8 @@ def configure_app(app, version=''):
         ('revisions/{revision_id}/validations/{validation_name}'
          '/entries/{entry_id}',
             validations.ValidationsResource()),
-        ('rollback/{revision_id}', rollback.RollbackResource())
+        # min=0 is used as revision rollback supports 0.
+        ('rollback/{revision_id:int(min=0)}', rollback.RollbackResource())
     ]
 
     for path, res in v1_0_routes:

deckhand/tests/unit/control/test_api_initialization.py

@@ -99,8 +99,6 @@ class TestApi(test_base.DeckhandTestCase):
                       self.revision_tags_resource()),
             mock.call('/api/v1.0/revisions/{revision_id}/tags/{tag}',
                       self.revision_tags_resource()),
-            mock.call('/api/v1.0/rollback/{revision_id}',
-                      self.rollback_resource()),
             mock.call('/api/v1.0/revisions/{revision_id}/validations',
                       self.validations_resource()),
             mock.call('/api/v1.0/revisions/{revision_id}/validations/'
@@ -109,6 +107,8 @@ class TestApi(test_base.DeckhandTestCase):
             mock.call('/api/v1.0/revisions/{revision_id}/validations/'
                       '{validation_name}/entries/{entry_id}',
                       self.validations_resource()),
+            mock.call('/api/v1.0/rollback/{revision_id:int(min=0)}',
+                      self.rollback_resource()),
             mock.call('/versions', self.versions_resource())
         ], any_order=True)
 

deckhand/tests/unit/control/test_revisions_rollback_controller.py

@@ -21,6 +21,37 @@ from deckhand import factories
 from deckhand.tests.unit.control import base as test_base
 
 
+class TestRevisionsRollbackController(test_base.BaseControllerTest):
+    """Test basic scenarios for the ``RollbackResource`` controller."""
+
+    def test_rollback_to_revision_0(self):
+        rules = {'deckhand:create_cleartext_documents': '@',
+                 'deckhand:list_revisions': '@'}
+        self.policy.set_rules(rules)
+
+        # Create revision 1.
+        documents_factory = factories.DocumentFactory(1, [1])
+        payload = documents_factory.gen_test({})
+        resp = self.app.simulate_put(
+            '/api/v1.0/buckets/mop/documents',
+            headers={'Content-Type': 'application/x-yaml'},
+            body=yaml.safe_dump_all(payload))
+        self.assertEqual(200, resp.status_code)
+
+        # Rollback to revision 0 (thereby creating revision 1 in effect).
+        resp = self.app.simulate_post(
+            '/api/v1.0/rollback/%s' % 0,
+            headers={'Content-Type': 'application/x-yaml'})
+        self.assertEqual(201, resp.status_code)
+
+        # Validate that 2 revisions now exist.
+        resp = self.app.simulate_get(
+            '/api/v1.0/revisions',
+            headers={'Content-Type': 'application/x-yaml'})
+        self.assertEqual(200, resp.status_code)
+        self.assertEqual(2, yaml.safe_load(resp.text)['count'])
+
+
 class TestRevisionsRollbackControllerNegativeRBAC(
         test_base.BaseControllerTest):
     """Test suite for validating negative RBAC scenarios for revisions rollback

requirements.txt

@@ -8,7 +8,7 @@ alembic==1.0.1
 beaker==1.9.1
 cryptography==2.3.1
 deepdiff==3.3.0
-falcon==1.2.0
+falcon==1.4.1
 jsonpath-ng==1.4.3
 jsonschema==2.6.0
 keystoneauth1==3.4.0