Fix an error handling case in instance info

[ganeti-local] / lib / backend.py

diff --git a/lib/backend.py b/lib/backend.py
index 4839c61..c896875 100644 (file)
--- a/lib/backend.py
+++ b/lib/backend.py
@@ -597,6 +597,30 @@ def GetInstanceInfo(instance, hname):
   return output
 
 
+def GetInstanceMigratable(instance):
+  """Gives whether an instance can be migrated.
+
+  @type instance: L{objects.Instance}
+  @param instance: object representing the instance to be checked.
+
+  @rtype: tuple
+  @return: tuple of (result, description) where:
+      - result: whether the instance can be migrated or not
+      - description: a description of the issue, if relevant
+
+  """
+  hyper = hypervisor.GetHypervisor(instance.hypervisor)
+  if instance.name not in hyper.ListInstances():
+    return (False, 'not running')
+
+  for idx in range(len(instance.disks)):
+    link_name = _GetBlockDevSymlinkPath(instance.name, idx)
+    if not os.path.islink(link_name):
+      return (False, 'not restarted since ganeti 1.2.5')
+
+  return (True, '')
+
+
 def GetAllInstancesInfo(hypervisor_list):
   """Gather data about all instances.
 
@@ -733,27 +757,29 @@ def _GetVGInfo(vg_name):
   return retdic
 
 
-def _SymlinkBlockDev(instance_name, device_path, device_name):
+def _GetBlockDevSymlinkPath(instance_name, idx):
+  return os.path.join(constants.DISK_LINKS_DIR,
+                      "%s:%d" % (instance_name, idx))
+
+
+def _SymlinkBlockDev(instance_name, device_path, idx):
   """Set up symlinks to a instance's block device.
 
   This is an auxiliary function run when an instance is start (on the primary
   node) or when an instance is migrated (on the target node).
 
-  Args:
-    instance_name: the name of the target instance
-    device_path: path of the physical block device, on the node
-    device_name: 'virtual' name of the device
 
-  Returns:
-    absolute path to the disk's symlink
+  @param instance_name: the name of the target instance
+  @param device_path: path of the physical block device, on the node
+  @param idx: the disk index
+  @return: absolute path to the disk's symlink
 
   """
-  link_basename = "%s-%s" % (instance_name, device_name)
-  link_name = os.path.join(constants.DISK_LINKS_DIR, link_basename)
+  link_name = _GetBlockDevSymlinkPath(instance_name, idx)
   try:
     os.symlink(device_path, link_name)
-  except OSError, e:
-    if e.errno == errno.EEXIST:
+  except OSError, err:
+    if err.errno == errno.EEXIST:
       if (not os.path.islink(link_name) or
           os.readlink(link_name) != device_path):
         os.remove(link_name)
@@ -764,6 +790,19 @@ def _SymlinkBlockDev(instance_name, device_path, device_name):
   return link_name
 
 
+def _RemoveBlockDevLinks(instance_name, disks):
+  """Remove the block device symlinks belonging to the given instance.
+
+  """
+  for idx, disk in enumerate(disks):
+    link_name = _GetBlockDevSymlinkPath(instance_name, idx)
+    if os.path.islink(link_name):
+      try:
+        os.remove(link_name)
+      except OSError:
+        logging.exception("Can't remove symlink '%s'", link_name)
+
+
 def _GatherAndLinkBlockDevs(instance):
   """Set up an instance's block device(s).
 
@@ -784,8 +823,7 @@ def _GatherAndLinkBlockDevs(instance):
                                     str(disk))
     device.Open()
     try:
-      link_name = _SymlinkBlockDev(instance.name, device.dev_path,
-                                   "disk%d" % idx)
+      link_name = _SymlinkBlockDev(instance.name, device.dev_path, idx)
     except OSError, e:
       raise errors.BlockDeviceError("Cannot create block device symlink: %s" %
                                     e.strerror)
@@ -818,6 +856,7 @@ def StartInstance(instance, extra_args):
     return False
   except errors.HypervisorError, err:
     logging.exception("Failed to start instance")
+    _RemoveBlockDevLinks(instance.name, instance.disks)
     return False
 
   return True
@@ -870,6 +909,8 @@ def ShutdownInstance(instance):
                     instance.name)
       return False
 
+  _RemoveBlockDevLinks(instance.name, instance.disks)
+
   return True
 
 
@@ -2056,12 +2097,14 @@ def JobQueueSetDrainFlag(drain_flag):
   return True
 
 
-def CloseBlockDevices(disks):
+def CloseBlockDevices(instance_name, disks):
   """Closes the given block devices.
 
   This means they will be switched to secondary mode (in case of
   DRBD).
 
+  @param instance_name: if the argument is not empty, the symlinks
+      of this instance will be removed
   @type disks: list of L{objects.Disk}
   @param disks: the list of disks to be closed
   @rtype: tuple (success, message)
@@ -2087,6 +2130,8 @@ def CloseBlockDevices(disks):
   if msg:
     return (False, "Can't make devices secondary: %s" % ",".join(msg))
   else:
+    if instance_name:
+      _RemoveBlockDevLinks(instance_name, disks)
     return (True, "All devices secondary")