Snapshots/backups can no longer happen simultaneously. Tests included.

Implemented exception.InstanceBusy when attempting to snapshot/backup an
instance which is already snapshotting or being currently backed up.

Fixes bug 727502.

(Patch Set 2) 3 new exceptions: InstanceBusy, InstanceSnapshotting, and InstanceBackingUp
(Patch Set 3) Oops. New exceptions now inherit from InstanceBusy
(Patch Set 4) Tests now tear down created instances

(cherry picked from commit b5abd8e)

Change-Id: I42a04254bd96d5f7a92b71a5d3e79f0350bbda5b

nova/api/openstack/images.py

@@ -124,10 +124,15 @@ def create(self, req, body):
 
         context = req.environ["nova.context"]
         props = {'instance_id': instance_id}
-        image = self._compute_service.snapshot(context,
-                                          instance_id,
-                                          image_name,
-                                          extra_properties=props)
+
+        try:
+            image = self._compute_service.snapshot(context,
+                                              instance_id,
+                                              image_name,
+                                              extra_properties=props)
+        except exception.InstanceBusy:
+            msg = _("Server is currently creating an image. Please wait.")
+            raise webob.exc.HTTPConflict(explanation=msg)
 
         return dict(image=self.get_builder(req).build(image, detail=True))
 

nova/api/openstack/servers.py

@@ -811,10 +811,14 @@ def _action_create_image(self, input_dict, req, instance_id):
             msg = _("Invalid metadata")
             raise webob.exc.HTTPBadRequest(explanation=msg)
 
-        image = self.compute_api.snapshot(context,
-                                          instance_id,
-                                          image_name,
-                                          extra_properties=props)
+        try:
+            image = self.compute_api.snapshot(context,
+                                              instance_id,
+                                              image_name,
+                                              extra_properties=props)
+        except exception.InstanceBusy:
+            msg = _("Server is currently creating an image. Please wait.")
+            raise webob.exc.HTTPConflict(explanation=msg)
 
         # build location of newly-created image entity
         image_id = str(image['id'])

nova/compute/api.py

@@ -1028,6 +1028,14 @@ def _create_image(self, context, instance_id, name, image_type,
 
         """
         instance = self.db.instance_get(context, instance_id)
+        task_state = instance["task_state"]
+
+        if task_state == task_states.IMAGE_BACKUP:
+            raise exception.InstanceBackingUp(instance_id=instance_id)
+
+        if task_state == task_states.IMAGE_SNAPSHOT:
+            raise exception.InstanceSnapshotting(instance_id=instance_id)
+
         properties = {'instance_uuid': instance['uuid'],
                       'user_id': str(context.user_id),
                       'image_state': 'creating',

nova/exception.py

@@ -182,6 +182,18 @@ class AdminRequired(NotAuthorized):
     message = _("User does not have admin privileges")
 
 
+class InstanceBusy(NovaException):
+    message = _("Instance %(instance_id)s is busy. (%(task_state)s)")
+
+
+class InstanceSnapshotting(InstanceBusy):
+    message = _("Instance %(instance_id)s is currently snapshotting.")
+
+
+class InstanceBackingUp(InstanceBusy):
+    message = _("Instance %(instance_id)s is currently being backed up.")
+
+
 class Invalid(NovaException):
     message = _("Unacceptable parameters.")
 

nova/tests/api/openstack/test_servers.py

@@ -1626,6 +1626,23 @@ def test_create_instance_no_name(self):
         res = req.get_response(fakes.wsgi_app())
         self.assertEqual(res.status_int, 400)
 
+    def test_create_image_conflict_snapshot_v1_1(self):
+        """Attempt to create image when image is already being created."""
+        def snapshot(*args, **kwargs):
+            raise exception.InstanceSnapshotting
+        self.stubs.Set(nova.compute.API, 'snapshot', snapshot)
+
+        req = webob.Request.blank('/v1.1/fakes/servers/1/action')
+        req.method = 'POST'
+        req.body = json.dumps({
+            "createImage": {
+                "name": "test_snapshot",
+            },
+        })
+        req.headers["content-type"] = "application/json"
+        res = req.get_response(fakes.wsgi_app())
+        self.assertEqual(res.status_int, 409)
+
     def test_create_instance_nonstring_name(self):
         self._setup_for_create_instance()
 

nova/tests/test_compute.py

@@ -24,6 +24,7 @@
 from nova.compute import instance_types
 from nova.compute import manager as compute_manager
 from nova.compute import power_state
+from nova.compute import task_states
 from nova.compute import vm_states
 from nova import context
 from nova import db
@@ -352,6 +353,36 @@ def test_snapshot(self):
         self.compute.snapshot_instance(self.context, instance_id, name)
         self.compute.terminate_instance(self.context, instance_id)
 
+    def test_snapshot_conflict_backup(self):
+        """Can't backup an instance which is already being backed up."""
+        instance_id = self._create_instance()
+        instance_values = {'task_state': task_states.IMAGE_BACKUP}
+        db.instance_update(self.context, instance_id, instance_values)
+
+        self.assertRaises(exception.InstanceBackingUp,
+                          self.compute_api.backup,
+                          self.context,
+                          instance_id,
+                          None,
+                          None,
+                          None)
+
+        db.instance_destroy(self.context, instance_id)
+
+    def test_snapshot_conflict_snapshot(self):
+        """Can't snapshot an instance which is already being snapshotted."""
+        instance_id = self._create_instance()
+        instance_values = {'task_state': task_states.IMAGE_SNAPSHOT}
+        db.instance_update(self.context, instance_id, instance_values)
+
+        self.assertRaises(exception.InstanceSnapshotting,
+                          self.compute_api.snapshot,
+                          self.context,
+                          instance_id,
+                          None)
+
+        db.instance_destroy(self.context, instance_id)
+
     def test_console_output(self):
         """Make sure we can get console output from instance"""
         instance_id = self._create_instance()