nova/doc/api_samples/os-preserve-ephemeral-rebuild/server-action-rebuild-preserve-ephemeral.json

{
    "rebuild": {
        "imageRef": "70a599e0-31e7-49b7-b260-868f441e862b",
        "name": "foobar",
        "adminPass": "seekr3t",
        "metadata": {
            "meta_var": "meta_val"
        },
        "preserve_ephemeral": false
    }
}