Xen: implement auxiliary migration functions

These are used, for the xen hypervisor, to copy the xen config file to
the remote node. This breaks migration for instances which have been
migrated, but not restarted, with the old code, for which the config
file was just lost.

Reviewed-by: iustinp

diff --git a/lib/hypervisor/hv_xen.py b/lib/hypervisor/hv_xen.py
index 1bbb611..42ce709 100644 (file)
--- a/lib/hypervisor/hv_xen.py
+++ b/lib/hypervisor/hv_xen.py
@@ -51,6 +51,26 @@ class XenHypervisor(hv_base.BaseHypervisor):
     raise NotImplementedError
 
   @staticmethod
+  def _WriteConfigFileStatic(instance_name, data):
+    """Write the Xen config file for the instance.
+
+    This version of the function just writes the config file from static data.
+
+    """
+    utils.WriteFile("/etc/xen/%s" % instance_name, data=data)
+
+  @staticmethod
+  def _ReadConfigFile(instance_name):
+    """Returns the contents of the instance config file.
+
+    """
+    try:
+      file_content = utils.ReadFile("/etc/xen/%s" % instance_name)
+    except EnvironmentError, err:
+      raise errors.HypervisorError("Failed to load Xen config file: %s" % err)
+    return file_content
+
+  @staticmethod
   def _RemoveConfigFile(instance_name):
     """Remove the xen configuration file.
 
@@ -266,6 +286,47 @@ class XenHypervisor(hv_base.BaseHypervisor):
 
     return disk_data
 
+  def MigrationInfo(self, instance):
+    """Get instance information to perform a migration.
+
+    @type instance: L{objects.Instance}
+    @param instance: instance to be migrated
+    @rtype: string
+    @return: content of the xen config file
+
+    """
+    return self._ReadConfigFile(instance.name)
+
+  def AcceptInstance(self, instance, info, target):
+    """Prepare to accept an instance.
+
+    @type instance: L{objects.Instance}
+    @param instance: instance to be accepted
+    @type info: string
+    @param info: content of the xen config file on the source node
+    @type target: string
+    @param target: target host (usually ip), on this node
+
+    """
+    pass
+
+  def FinalizeMigration(self, instance, info, success):
+    """Finalize an instance migration.
+
+    After a successful migration we write the xen config file.
+    We do nothing on a failure, as we did not change anything at accept time.
+
+    @type instance: L{objects.Instance}
+    @param instance: instance whose migration is being aborted
+    @type info: string
+    @param info: content of the xen config file on the source node
+    @type success: boolean
+    @param success: whether the migration was a success or a failure
+
+    """
+    if success:
+      self._WriteConfigFileStatic(instance.name, info)
+
   def MigrateInstance(self, instance, target, live):
     """Migrate an instance to a target node.