On Mon, Dec 20, 2021 at 9:59 PM Nathanaël Blanchet <blanchet(a)abes.fr&gt; wrote: Adding the devel list since question is more about extending oVirt ... So you want to run the clean hook only if stop reason == "clean"? I think the way to integrate hooks is to define a custom property in the vm, and check if the property was defined in the hook. For example how the localdisk hook is triggered: def main(): backend = os.environ.get('localdisk') if backend is None: return if backend not in [BACKEND_LVM, BACKEND_LVM_THIN]: hooking.log("localdisk-hook: unsupported backend: %r" % backend) return ... The hook runs only if the environment variable "localdisk" is defined and configured properly. vdsm defines the custom properties as environment variables. On the engine side, you need to add a user defined property: engine-config -s UserDefinedVMProperties='localdisk=^(lvm|lvmthin)$' And configure a custom property with one of the allowed values, like: localdisk=lvm See vdsm_hooks/localdisk/README for more info. If you want to control the cleanup, by adding a "clean" stop reason only when needed, this will not help, and vdsm hook is probably not the right way to integrate this. If your intent is to clean a vm in some special events, but you want to integrate this in engine, maybe you should write an engine ui plugin? The plugin can show the running vms, and provide a clean button that will shut down the vm and run your custom code. But maybe you don't need to integrate this in engine, and having a simple script using ovirt engine API/SDK to shutdown the vm and run the cleanup code. Nir