Cells: Reduce the create_image call depth for cells

This patch reduces the create image call depth (for snapshot/backup) by
returning the basic image details to the user before we call down to
the child cell.  The image entry is created in glance immediately, and
the child cell will finish up the rest.

Implements blueprint nova-compute-cells

Change-Id: I048cc532614c602f3aa6b539fb51e951174e4598

2 files changed, 112 insertions, 4 deletions

diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index b79fbd042..7fac63e09 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -4376,6 +4376,31 @@ class ComputeAPITestCase(BaseTestCase):
 
         db.instance_destroy(self.context, instance['uuid'])
 
+    def test_snapshot_given_image_uuid(self):
+        """Ensure a snapshot of an instance can be created when image UUID
+        is already known.
+        """
+        instance = self._create_fake_instance()
+        name = 'snap1'
+        extra_properties = {'extra_param': 'value1'}
+        recv_meta = self.compute_api.snapshot(self.context, instance, name,
+                                              extra_properties)
+        image_id = recv_meta['id']
+
+        def fake_show(meh, context, id):
+            return recv_meta
+
+        instance = db.instance_update(self.context, instance['uuid'],
+                {'task_state': None})
+        fake_image.stub_out_image_service(self.stubs)
+        self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
+        image = self.compute_api.snapshot(self.context, instance, name,
+                                          extra_properties,
+                                          image_id=image_id)
+        self.assertEqual(image, recv_meta)
+
+        db.instance_destroy(self.context, instance['uuid'])
+
     def test_snapshot_minram_mindisk_VHD(self):
         """Ensure a snapshots min_ram and min_disk are correct.
 
@@ -4467,7 +4492,10 @@ class ComputeAPITestCase(BaseTestCase):
         def fake_show(*args):
             raise exception.ImageNotFound(image_id="fake")
 
-        self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
+        if not self.__class__.__name__ == "CellsComputeAPITestCase":
+            # Cells tests will call this a 2nd time in child cell with
+            # the newly created image_id, and we want that one to succeed.
+            self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
 
         instance = self._create_fake_instance()
 
diff --git a/nova/tests/compute/test_compute_cells.py b/nova/tests/compute/test_compute_cells.py
index aa4b448d4..3c25f9b43 100644
--- a/nova/tests/compute/test_compute_cells.py
+++ b/nova/tests/compute/test_compute_cells.py
@@ -16,7 +16,11 @@
 """
 Tests For Compute w/ Cells
 """
+import functools
+
 from nova.compute import cells_api as compute_cells_api
+from nova import db
+from nova.openstack.common import jsonutils
 from nova.openstack.common import log as logging
 from nova.tests.compute import test_compute
 
@@ -28,17 +32,57 @@ ORIG_COMPUTE_API = None
 
 def stub_call_to_cells(context, instance, method, *args, **kwargs):
     fn = getattr(ORIG_COMPUTE_API, method)
+    original_instance = kwargs.pop('original_instance', None)
+    if original_instance:
+        instance = original_instance
+        # Restore this in 'child cell DB'
+        db.instance_update(context, instance['uuid'],
+                dict(vm_state=instance['vm_state'],
+                     task_state=instance['task_state']))
+
     return fn(context, instance, *args, **kwargs)
 
 
 def stub_cast_to_cells(context, instance, method, *args, **kwargs):
     fn = getattr(ORIG_COMPUTE_API, method)
+    original_instance = kwargs.pop('original_instance', None)
+    if original_instance:
+        instance = original_instance
+        # Restore this in 'child cell DB'
+        db.instance_update(context, instance['uuid'],
+                dict(vm_state=instance['vm_state'],
+                     task_state=instance['task_state']))
     fn(context, instance, *args, **kwargs)
 
 
-def deploy_stubs(stubs, api):
-    stubs.Set(api, '_call_to_cells', stub_call_to_cells)
-    stubs.Set(api, '_cast_to_cells', stub_cast_to_cells)
+def deploy_stubs(stubs, api, original_instance=None):
+    call = stub_call_to_cells
+    cast = stub_cast_to_cells
+
+    if original_instance:
+        kwargs = dict(original_instance=original_instance)
+        call = functools.partial(stub_call_to_cells, **kwargs)
+        cast = functools.partial(stub_cast_to_cells, **kwargs)
+
+    stubs.Set(api, '_call_to_cells', call)
+    stubs.Set(api, '_cast_to_cells', cast)
+
+
+def wrap_create_instance(func):
+    @functools.wraps(func)
+    def wrapper(self, *args, **kwargs):
+        instance = self._create_fake_instance()
+
+        def fake(*args, **kwargs):
+            return instance
+
+        self.stubs.Set(self, '_create_fake_instance', fake)
+        original_instance = jsonutils.to_primitive(instance)
+        deploy_stubs(self.stubs, self.compute_api,
+                     original_instance=original_instance)
+        return func(self, *args, **kwargs)
+
+    return wrapper
 
 
 class CellsComputeAPITestCase(test_compute.ComputeAPITestCase):
@@ -84,6 +128,42 @@ class CellsComputeAPITestCase(test_compute.ComputeAPITestCase):
     def test_get_backdoor_port(self):
         self.skipTest("Test is incompatible with cells.")
 
+    def test_snapshot_given_image_uuid(self):
+        self.skipTest("Test doesn't apply to API cell.")
+
+    @wrap_create_instance
+    def test_snapshot(self):
+        return super(CellsComputeAPITestCase, self).test_snapshot()
+
+    @wrap_create_instance
+    def test_snapshot_image_metadata_inheritance(self):
+        return super(CellsComputeAPITestCase,
+                self).test_snapshot_image_metadata_inheritance()
+
+    @wrap_create_instance
+    def test_snapshot_minram_mindisk(self):
+        return super(CellsComputeAPITestCase,
+                self).test_snapshot_minram_mindisk()
+
+    @wrap_create_instance
+    def test_snapshot_minram_mindisk_VHD(self):
+        return super(CellsComputeAPITestCase,
+                self).test_snapshot_minram_mindisk_VHD()
+
+    @wrap_create_instance
+    def test_snapshot_minram_mindisk_img_missing_minram(self):
+        return super(CellsComputeAPITestCase,
+                self).test_snapshot_minram_mindisk_img_missing_minram()
+
+    @wrap_create_instance
+    def test_snapshot_minram_mindisk_no_image(self):
+        return super(CellsComputeAPITestCase,
+                self).test_snapshot_minram_mindisk_no_image()
+
+    @wrap_create_instance
+    def test_backup(self):
+        return super(CellsComputeAPITestCase, self).test_backup()
+
 
 class CellsComputePolicyTestCase(test_compute.ComputePolicyTestCase):
     def setUp(self):