A.4. The VDSM Hook Domain XML Object

VDSM uses the libvirt domain XML format to define virtual machines. The UUID of the virtual machine may be deduced from the domain XML, but it is also available as the environment variable vmId.

When hook scripts are started, the _hook_domxml variable is appended to the environment. This variable contains the path of the libvirt domain XML representation of the relevant virtual machine.

Some hooks are an exception to this rule. The following hooks contain the XML representation of the NIC, not the virtual machine:

  • *_nic_hotplug_*
  • *_nic_hotunplug_*
  • *_update_device
  • *_device_create
  • *_device_migrate_*

The before_migration_destination and before_dehibernation hooks currently receive the domain XML from the source host. The domain XML at the destination will be different.