Implement snapshots for raw backend

blueprint snapshots-for-everyone

Use simple qemu-img convert for raw snapshots.
Polymorphically select snapshot behavior for
raw and qcow2.
Allow images to be constructed from actual device/file path.

Change-Id: I6a57e43c6775c144c41a53382dcc7504ce6d4c43

nova/tests/fake_imagebackend.py

@@ -37,6 +37,9 @@ class Backend(object):
             def cache(self, fetch_func, filename, size=None, *args, **kwargs):
                 pass
 
+            def snapshot(self, name):
+                pass
+
             def libvirt_info(self, disk_bus, disk_dev, device_type,
                              cache_mode):
                 info = config.LibvirtConfigGuestDisk()
@@ -50,3 +53,8 @@ class Backend(object):
                 return info
 
         return FakeImage(instance, name)
+
+    def snapshot(self, path, name, image_type=''):
+        #NOTE(bfilippov): this is done in favor for
+        # snapshot tests in test_libvirt.LibvirtConnTestCase
+        return imagebackend.Backend(True).snapshot(path, name, image_type)

nova/tests/fake_libvirt_utils.py

@@ -104,7 +104,7 @@ def file_open(path, mode=None):
 
 
 def find_disk(virt_dom):
-    return "some/path"
+    return "filename"
 
 
 def load_file(path):
@@ -115,6 +115,10 @@ def load_file(path):
         return ''
 
 
+def logical_volume_info(path):
+    return {}
+
+
 def file_delete(path):
     return True
 

nova/tests/test_libvirt.py

@@ -53,6 +53,7 @@ from nova.virt.libvirt import config
 from nova.virt.libvirt import driver as libvirt_driver
 from nova.virt.libvirt import firewall
 from nova.virt.libvirt import imagebackend
+from nova.virt.libvirt import snapshots
 from nova.virt.libvirt import utils as libvirt_utils
 from nova.virt.libvirt import volume
 from nova.virt.libvirt import volume_nfs
@@ -484,6 +485,7 @@ class LibvirtConnTestCase(test.TestCase):
         self.flags(libvirt_snapshots_directory='')
         self.call_libvirt_dependant_setup = False
         libvirt_driver.libvirt_utils = fake_libvirt_utils
+        snapshots.libvirt_utils = fake_libvirt_utils
 
         def fake_extend(image, size):
             pass
@@ -532,7 +534,7 @@ class LibvirtConnTestCase(test.TestCase):
     def fake_lookup(self, instance_name):
         return FakeVirtDomain()
 
-    def fake_execute(self, *args):
+    def fake_execute(self, *args, **kwargs):
         open(args[-1], "a").close()
 
     def create_service(self, **kwargs):
@@ -1129,6 +1131,7 @@ class LibvirtConnTestCase(test.TestCase):
         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()
 
@@ -1164,6 +1167,11 @@ class LibvirtConnTestCase(test.TestCase):
         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)
@@ -1197,6 +1205,7 @@ class LibvirtConnTestCase(test.TestCase):
         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()