--Stolen from https://code.launchpad.net/~cerberus/nova/lp809909/+merge/68602

Fixes lp809909

Migrate of instance with no local storage fails with exception

Simply checks to see if the instance has any local storage, and if not, skips over the resize VDI step.

3 files changed, 26 insertions, 17 deletions

diff --git a/nova/virt/driver.py b/nova/virt/driver.py
index 34dc5f544..b219fb2cb 100644
--- a/nova/virt/driver.py
+++ b/nova/virt/driver.py
@@ -122,11 +122,12 @@ class ComputeDriver(object):
         """Create snapshot from a running VM instance."""
         raise NotImplementedError()
 
-    def finish_resize(self, instance, disk_info):
+    def finish_migration(self, instance, disk_info, network_info,
+                         resize_instance):
         """Completes a resize, turning on the migrated instance"""
         raise NotImplementedError()
 
-    def revert_resize(self, instance):
+    def revert_migration(self, instance):
         """Reverts a resize, powering back on the instance"""
         raise NotImplementedError()
 
diff --git a/nova/virt/xenapi/vmops.py b/nova/virt/xenapi/vmops.py
index 77efe1bf0..38ecc47c9 100644
--- a/nova/virt/xenapi/vmops.py
+++ b/nova/virt/xenapi/vmops.py
@@ -110,17 +110,19 @@ class VMOps(object):
                 instance_infos.append(instance_info)
         return instance_infos
 
-    def revert_resize(self, instance):
+    def revert_migration(self, instance):
         vm_ref = VMHelper.lookup(self._session, instance.name)
         self._start(instance, vm_ref)
 
-    def finish_resize(self, instance, disk_info, network_info):
+    def finish_migration(self, instance, disk_info, network_info,
+                      resize_instance):
         vdi_uuid = self.link_disks(instance, disk_info['base_copy'],
                 disk_info['cow'])
         vm_ref = self._create_vm(instance,
                                  [dict(vdi_type='os', vdi_uuid=vdi_uuid)],
                                  network_info)
-        self.resize_instance(instance, vdi_uuid)
+        if resize_instance:
+            self.resize_instance(instance, vdi_uuid)
         self._spawn(instance, vm_ref)
 
     def _start(self, instance, vm_ref=None):
@@ -568,18 +570,22 @@ class VMOps(object):
         return new_cow_uuid
 
     def resize_instance(self, instance, vdi_uuid):
-        """Resize a running instance by changing it's RAM and disk size."""
+        """Resize a running instance by changing its RAM and disk size."""
         #TODO(mdietz): this will need to be adjusted for swap later
         #The new disk size must be in bytes
 
-        new_disk_size = str(instance.local_gb * 1024 * 1024 * 1024)
-        instance_name = instance.name
-        instance_local_gb = instance.local_gb
-        LOG.debug(_("Resizing VDI %(vdi_uuid)s for instance %(instance_name)s."
-                " Expanding to %(instance_local_gb)d GB") % locals())
-        vdi_ref = self._session.call_xenapi('VDI.get_by_uuid', vdi_uuid)
-        self._session.call_xenapi('VDI.resize_online', vdi_ref, new_disk_size)
-        LOG.debug(_("Resize instance %s complete") % (instance.name))
+        new_disk_size = instance.local_gb * 1024 * 1024 * 1024
+        if new_disk_size > 0:
+            instance_name = instance.name
+            instance_local_gb = instance.local_gb
+            LOG.debug(_("Resizing VDI %(vdi_uuid)s for instance"
+                        "%(instance_name)s. Expanding to %(instance_local_gb)d"
+                        " GB") % locals())
+            vdi_ref = self._session.call_xenapi('VDI.get_by_uuid', vdi_uuid)
+            # for an instance with no local storage
+            self._session.call_xenapi('VDI.resize_online', vdi_ref,
+                    str(new_disk_size))
+            LOG.debug(_("Resize instance %s complete") % (instance.name))
 
     def reboot(self, instance):
         """Reboot VM instance."""
diff --git a/nova/virt/xenapi_conn.py b/nova/virt/xenapi_conn.py
index cddb8203b..cc18ed83c 100644
--- a/nova/virt/xenapi_conn.py
+++ b/nova/virt/xenapi_conn.py
@@ -191,13 +191,15 @@ class XenAPIConnection(driver.ComputeDriver):
         """Create VM instance"""
         self._vmops.spawn(instance, network_info)
 
-    def revert_resize(self, instance):
+    def revert_migration(self, instance):
         """Reverts a resize, powering back on the instance"""
         self._vmops.revert_resize(instance)
 
-    def finish_resize(self, instance, disk_info, network_info):
+    def finish_migration(self, instance, disk_info, network_info,
+                         resize_instance=False):
         """Completes a resize, turning on the migrated instance"""
-        self._vmops.finish_resize(instance, disk_info, network_info)
+        self._vmops.finish_migration(instance, disk_info, network_info,
+                                  resize_instance)
 
     def snapshot(self, instance, image_id):
         """ Create snapshot from a running VM instance """