let node_role_contract = [| 'ControlPlane, 'Worker, 'LoadBalancer |] in

let scale_template_contract = {
  server_type      | String,
  location         | String,
  hostname_pattern | String,
  private_network  | String,
  ip_range_prefix  | String,
  formula_id       | String | optional,
  image_role       | String | optional,
  os_type          | String | optional,
  architecture     | String | optional,
} in

let scale_policy_contract = {
  role     | node_role_contract,
  min      | Number,
  max      | Number,
  template | scale_template_contract,
} in

{
  NodeRole      = node_role_contract,
  ScaleTemplate = scale_template_contract,
  ScalePolicy   = scale_policy_contract,
}