fix: VM disks list would be wrong after a snap revert

The list of VDIs of a VM would be changed following a snapshot revert.
It would result in not having the correct list when destroying a VM and
leaving VDIs behind.
This fix make the `Snapshot.revert()` call refresh the VDI list of the
VM object it was created from.

Signed-off-by: Damien Thenot <[email protected]>

Author: Nambrok

lib/snapshot.py

@@ -2,7 +2,18 @@
 
 from lib.basevm import BaseVM
 
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from lib.host import Host
+    from lib.vm import VM
+
+
 class Snapshot(BaseVM):
+    def __init__(self, uuid: str, host: "Host", vm: "VM"):
+        self.basevm = vm
+        super(Snapshot, self).__init__(uuid, host)
+
     def _disk_list(self):
         return self.host.xe('snapshot-disk-list', {'uuid': self.uuid, 'vbd-params': ''},
                             minimal=True)
@@ -21,3 +32,4 @@ def exists(self):
     def revert(self):
         logging.info("Revert to snapshot %s", self.uuid)
         self.host.xe('snapshot-revert', {'uuid': self.uuid})
+        self.basevm.create_vdis_list() # We reset the base VM object VDIs list because it changed following the revert

lib/vm.py

@@ -34,15 +34,7 @@ def __init__(self, uuid: str, host: 'Host'):
         self.previous_host = None # previous host when migrated or being migrated
         self.is_windows = self.param_get('platform', 'device_id', accept_unknown_key=True) == '0002'
         self.is_uefi = self.param_get('HVM-boot-params', 'firmware', accept_unknown_key=True) == 'uefi'
-        try:
-            self.vdis = [VDI(vdi_uuid, host=host) for vdi_uuid in self.vdi_uuids()]
-        except commands.SSHCommandFailed as e:
-            # Doesn't work with Dom0 since `vm-disk-list` doesn't work on it so we create empty list
-            if e.stdout == "Error: No matching VMs found":
-                logging.info("Couldn't get disks list. We are Dom0. Continuing...")
-                self.vdis = []
-            else:
-                raise
+        self.create_vdis_list()
 
     def power_state(self) -> str:
         return self.param_get('power-state')
@@ -289,13 +281,14 @@ def snapshot(self, ignore_vdis=None):
         args = {'uuid': self.uuid, 'new-name-label': 'Snapshot of %s' % self.uuid}
         if ignore_vdis:
             args['ignore-vdi-uuids'] = ','.join(ignore_vdis)
-        return Snapshot(self.host.xe('vm-snapshot', args), self.host)
+        snap_uuid = self.host.xe('vm-snapshot', args)
+        return Snapshot(snap_uuid, self.host, self)
 
     def checkpoint(self) -> Snapshot:
         logging.info("Checkpoint VM")
         return Snapshot(self.host.xe('vm-checkpoint', {'uuid': self.uuid,
                                                        'new-name-label': 'Checkpoint of %s' % self.uuid}),
-                        self.host)
+                        self.host, self)
 
     def connect_vdi(self, vdi: VDI, device: str = "autodetect") -> str:
         logging.info(f">> Plugging VDI {vdi.uuid} on VM {self.uuid}")
@@ -338,6 +331,18 @@ def destroy_vdi(self, vdi_uuid: str) -> None:
                 super().destroy_vdi(vdi_uuid)
                 break
 
+    def create_vdis_list(self) -> None:
+        """ Used to redo the VDIs list of the VM when reverting a snapshot. """
+        try:
+            self.vdis = [VDI(vdi_uuid, host=self.host) for vdi_uuid in self.vdi_uuids()]
+        except commands.SSHCommandFailed as e:
+            # Doesn't work with Dom0 since `vm-disk-list` doesn't work on it so we create empty list
+            if e.stdout == "Error: No matching VMs found":
+                logging.info("Couldn't get disks list. We are Dom0. Continuing...")
+                self.vdis = []
+            else:
+                raise
+
     def vifs(self):
         _vifs = []
         for vif_uuid in safe_split(self.host.xe('vif-list', {'vm-uuid': self.uuid}, minimal=True)):