Fixes bug Snapshotting LXC instance fails

Fixes bug 1058273.

The path of the disk for snapshotting LXC instance is debugged.
Also, virt_dom.managedSave(0) and self._create_domain(domain=virt_dom)
are not called for LXC instance, because they are supported by libvirt.

Change-Id: Idf8275a0222b2eb289e16dd245f7721e17fce21d

3 files changed, 204 insertions, 6 deletions

diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 43b4d4813..51ff35003 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -1210,6 +1210,45 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertEquals(snapshot['disk_format'], 'ami')
         self.assertEquals(snapshot['name'], snapshot_name)
 
+    def test_lxc_snapshot_in_ami_format(self):
+        self.flags(libvirt_snapshots_directory='./',
+                   libvirt_type='lxc')
+
+        # Start test
+        image_service = nova.tests.image.fake.FakeImageService()
+
+        # Assign different image_ref from nova/images/fakes for testing ami
+        test_instance = copy.deepcopy(self.test_instance)
+        test_instance["image_ref"] = 'c905cedb-7281-47e4-8a62-f26bc5fc4c77'
+
+        # Assuming that base image already exists in image_service
+        instance_ref = db.instance_create(self.context, test_instance)
+        properties = {'instance_id': instance_ref['id'],
+                      'user_id': str(self.context.user_id)}
+        snapshot_name = 'test-snap'
+        sent_meta = {'name': snapshot_name, 'is_public': False,
+                     'status': 'creating', 'properties': properties}
+        # Create new image. It will be updated in snapshot method
+        # To work with it from snapshot, the single image_service is needed
+        recv_meta = image_service.create(context, sent_meta)
+
+        self.mox.StubOutWithMock(libvirt_driver.LibvirtDriver, '_conn')
+        libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
+        self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
+        libvirt_driver.utils.execute = self.fake_execute
+        libvirt_driver.libvirt_utils.disk_type = "qcow2"
+
+        self.mox.ReplayAll()
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        conn.snapshot(self.context, instance_ref, recv_meta['id'])
+
+        snapshot = image_service.show(context, recv_meta['id'])
+        self.assertEquals(snapshot['properties']['image_state'], 'available')
+        self.assertEquals(snapshot['status'], 'active')
+        self.assertEquals(snapshot['disk_format'], 'ami')
+        self.assertEquals(snapshot['name'], snapshot_name)
+
     def test_snapshot_in_raw_format(self):
         self.flags(libvirt_snapshots_directory='./')
 
@@ -1249,6 +1288,46 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertEquals(snapshot['disk_format'], 'raw')
         self.assertEquals(snapshot['name'], snapshot_name)
 
+    def test_lxc_snapshot_in_raw_format(self):
+        self.flags(libvirt_snapshots_directory='./',
+                   libvirt_type='lxc')
+
+        # Start test
+        image_service = nova.tests.image.fake.FakeImageService()
+
+        # Assuming that base image already exists in image_service
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        properties = {'instance_id': instance_ref['id'],
+                      'user_id': str(self.context.user_id)}
+        snapshot_name = 'test-snap'
+        sent_meta = {'name': snapshot_name, 'is_public': False,
+                     'status': 'creating', 'properties': properties}
+        # Create new image. It will be updated in snapshot method
+        # To work with it from snapshot, the single image_service is needed
+        recv_meta = image_service.create(context, sent_meta)
+
+        self.mox.StubOutWithMock(libvirt_driver.LibvirtDriver, '_conn')
+        libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
+        self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
+        libvirt_driver.utils.execute = self.fake_execute
+        self.stubs.Set(libvirt_driver.libvirt_utils, 'disk_type', 'raw')
+
+        def convert_image(source, dest, out_format):
+            libvirt_driver.libvirt_utils.files[dest] = ''
+
+        images.convert_image = convert_image
+
+        self.mox.ReplayAll()
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        conn.snapshot(self.context, instance_ref, recv_meta['id'])
+
+        snapshot = image_service.show(context, recv_meta['id'])
+        self.assertEquals(snapshot['properties']['image_state'], 'available')
+        self.assertEquals(snapshot['status'], 'active')
+        self.assertEquals(snapshot['disk_format'], 'raw')
+        self.assertEquals(snapshot['name'], snapshot_name)
+
     def test_snapshot_in_qcow2_format(self):
         self.flags(snapshot_image_format='qcow2',
                    libvirt_snapshots_directory='./')
@@ -1284,6 +1363,42 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertEquals(snapshot['disk_format'], 'qcow2')
         self.assertEquals(snapshot['name'], snapshot_name)
 
+    def test_lxc_snapshot_in_qcow2_format(self):
+        self.flags(snapshot_image_format='qcow2',
+                   libvirt_snapshots_directory='./',
+                   libvirt_type='lxc')
+
+        # Start test
+        image_service = nova.tests.image.fake.FakeImageService()
+
+        # Assuming that base image already exists in image_service
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        properties = {'instance_id': instance_ref['id'],
+                      'user_id': str(self.context.user_id)}
+        snapshot_name = 'test-snap'
+        sent_meta = {'name': snapshot_name, 'is_public': False,
+                     'status': 'creating', 'properties': properties}
+        # Create new image. It will be updated in snapshot method
+        # To work with it from snapshot, the single image_service is needed
+        recv_meta = image_service.create(context, sent_meta)
+
+        self.mox.StubOutWithMock(libvirt_driver.LibvirtDriver, '_conn')
+        libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
+        self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
+        libvirt_driver.utils.execute = self.fake_execute
+        libvirt_driver.libvirt_utils.disk_type = "qcow2"
+
+        self.mox.ReplayAll()
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        conn.snapshot(self.context, instance_ref, recv_meta['id'])
+
+        snapshot = image_service.show(context, recv_meta['id'])
+        self.assertEquals(snapshot['properties']['image_state'], 'available')
+        self.assertEquals(snapshot['status'], 'active')
+        self.assertEquals(snapshot['disk_format'], 'qcow2')
+        self.assertEquals(snapshot['name'], snapshot_name)
+
     def test_snapshot_no_image_architecture(self):
         self.flags(libvirt_snapshots_directory='./')
 
@@ -1321,6 +1436,44 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertEquals(snapshot['status'], 'active')
         self.assertEquals(snapshot['name'], snapshot_name)
 
+    def test_lxc_snapshot_no_image_architecture(self):
+        self.flags(libvirt_snapshots_directory='./',
+                   libvirt_type='lxc')
+
+        # Start test
+        image_service = nova.tests.image.fake.FakeImageService()
+
+        # Assign different image_ref from nova/images/fakes for
+        # testing different base image
+        test_instance = copy.deepcopy(self.test_instance)
+        test_instance["image_ref"] = '76fa36fc-c930-4bf3-8c8a-ea2a2420deb6'
+
+        # Assuming that base image already exists in image_service
+        instance_ref = db.instance_create(self.context, test_instance)
+        properties = {'instance_id': instance_ref['id'],
+                      'user_id': str(self.context.user_id)}
+        snapshot_name = 'test-snap'
+        sent_meta = {'name': snapshot_name, 'is_public': False,
+                     'status': 'creating', 'properties': properties}
+        # Create new image. It will be updated in snapshot method
+        # To work with it from snapshot, the single image_service is needed
+        recv_meta = image_service.create(context, sent_meta)
+
+        self.mox.StubOutWithMock(libvirt_driver.LibvirtDriver, '_conn')
+        libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
+        self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
+        libvirt_driver.utils.execute = self.fake_execute
+
+        self.mox.ReplayAll()
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        conn.snapshot(self.context, instance_ref, recv_meta['id'])
+
+        snapshot = image_service.show(context, recv_meta['id'])
+        self.assertEquals(snapshot['properties']['image_state'], 'available')
+        self.assertEquals(snapshot['status'], 'active')
+        self.assertEquals(snapshot['name'], snapshot_name)
+
     def test_snapshot_no_original_image(self):
         self.flags(libvirt_snapshots_directory='./')
 
@@ -1354,6 +1507,40 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertEquals(snapshot['status'], 'active')
         self.assertEquals(snapshot['name'], snapshot_name)
 
+    def test_lxc_snapshot_no_original_image(self):
+        self.flags(libvirt_snapshots_directory='./',
+                   libvirt_type='lxc')
+
+        # Start test
+        image_service = nova.tests.image.fake.FakeImageService()
+
+        # Assign a non-existent image
+        test_instance = copy.deepcopy(self.test_instance)
+        test_instance["image_ref"] = '661122aa-1234-dede-fefe-babababababa'
+
+        instance_ref = db.instance_create(self.context, test_instance)
+        properties = {'instance_id': instance_ref['id'],
+                      'user_id': str(self.context.user_id)}
+        snapshot_name = 'test-snap'
+        sent_meta = {'name': snapshot_name, 'is_public': False,
+                     'status': 'creating', 'properties': properties}
+        recv_meta = image_service.create(context, sent_meta)
+
+        self.mox.StubOutWithMock(libvirt_driver.LibvirtDriver, '_conn')
+        libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
+        self.mox.StubOutWithMock(libvirt_driver.utils, 'execute')
+        libvirt_driver.utils.execute = self.fake_execute
+
+        self.mox.ReplayAll()
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        conn.snapshot(self.context, instance_ref, recv_meta['id'])
+
+        snapshot = image_service.show(context, recv_meta['id'])
+        self.assertEquals(snapshot['properties']['image_state'], 'available')
+        self.assertEquals(snapshot['status'], 'active')
+        self.assertEquals(snapshot['name'], snapshot_name)
+
     def test_attach_invalid_volume_type(self):
         self.create_fake_libvirt_mock()
         libvirt_driver.LibvirtDriver._conn.lookupByName = self.fake_lookup
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 2d3b1d954..8ef469b76 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -830,8 +830,10 @@ class LibvirtDriver(driver.ComputeDriver):
         (state, _max_mem, _mem, _cpus, _t) = virt_dom.info()
         state = LIBVIRT_POWER_STATE[state]
 
-        if state == power_state.RUNNING:
-            virt_dom.managedSave(0)
+        # NOTE(dkang): managedSave does not work for LXC
+        if FLAGS.libvirt_type != 'lxc':
+            if state == power_state.RUNNING:
+                virt_dom.managedSave(0)
 
         # Make the snapshot
         snapshot = self.image_backend.snapshot(disk_path, snapshot_name,
@@ -848,8 +850,11 @@ class LibvirtDriver(driver.ComputeDriver):
                 snapshot.extract(out_path, image_format)
             finally:
                 snapshot.delete()
-                if state == power_state.RUNNING:
-                    self._create_domain(domain=virt_dom)
+                # NOTE(dkang): because previous managedSave is not called
+                #              for LXC, _create_domain must not be called.
+                if FLAGS.libvirt_type != 'lxc':
+                    if state == power_state.RUNNING:
+                        self._create_domain(domain=virt_dom)
 
             # Upload that image to the image service
             with libvirt_utils.file_open(out_path) as image_file:
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 17c9efdda..8df923c9f 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -417,8 +417,14 @@ def find_disk(virt_dom):
     May be file or device"""
     xml_desc = virt_dom.XMLDesc(0)
     domain = etree.fromstring(xml_desc)
-    source = domain.find('devices/disk/source')
-    disk_path = source.get('file') or source.get('dev')
+    if FLAGS.libvirt_type == 'lxc':
+        source = domain.find('devices/filesystem/source')
+        disk_path = source.get('dir')
+        disk_path = disk_path[0:disk_path.rfind('rootfs')]
+        disk_path = os.path.join(disk_path, 'disk')
+    else:
+        source = domain.find('devices/disk/source')
+        disk_path = source.get('file') or source.get('dev')
 
     if not disk_path:
         raise RuntimeError(_("Can't retrieve root device path "