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A.10. Using the VDSM Hooking Module

VDSM ships with a Python hooking module, providing helper functions for VDSM hook scripts. This module is provided as an example, and is only relevant to VDSM hooks written in Python.

The hooking module supports reading of a virtual machine’s libvirt XML into a DOM object. Hook scripts can then use Python’s built in xml.dom library ( to manipulate the object.

The modified object can then be saved back to libvirt XML using the hooking module. The hooking module provides the following functions to support hook development:

Table A.2. Hooking module functions




Converts a string "true" or "false" to a Boolean value



Reads the virtual machine’s libvirt XML into a DOM object


DOM object

Writes the virtual machine’s libvirt XML from a DOM object