nova/doc/notification_samples/instance-live_migration_pre-start.json

{
    "event_type": "instance.live_migration_pre.start",
    "payload": {
        "$ref": "common_payloads/InstanceActionPayload.json#",
        "nova_object.data": {
            "task_state": "migrating"
        }
    },
    "priority": "INFO",
    "publisher_id": "nova-compute:host2"
}