I think we need another format of extended attrs
```
{
    "deployment": {
        "cluster_attr_1": 1,
        "cluster_attr_2": 2,
        "cluster_attr_3": 3
        "nodes": [{"id":1, "node_attrs_1": 1}]
    }
    "provisioning": {}
    "any_other_action": {}
}
```

And before deployment we take "deployment" structure and will merge it with nailgun structure.