~> **Note:** Use [google_compute_region_instance_group_manager](/docs/providers/google/r/compute_region_instance_group_manager.html) to create a regional (multi-zone) instance group manager.
group. You can specify only one value. Structure is documented below. For more information, see the [official documentation](https://cloud.google.com/compute/docs/instance-groups/creating-groups-of-managed-instances#monitoring_groups).
*`rolling_update_policy` - (Optional, [Beta](/docs/providers/google/index.html#beta-features)) The update policy for this managed instance group. Structure is documented below. For more information, see the [official documentation](https://cloud.google.com/compute/docs/instance-groups/updating-managed-instance-groups) and [API](https://cloud.google.com/compute/docs/reference/rest/beta/instanceGroupManagers/patch)
The **rolling_update_policy** block supports:
```hcl
rolling_update_policy{
type = "PROACTIVE"
minimal_action = "REPLACE"
max_surge_percent = 20
max_unavailable_fixed = 2
min_ready_sec = 50
}
```
*`minimal_action` - (Required) - Minimal action to be taken on an instance. Valid values are `"RESTART"`, `"REPLACE"`
*`type` - (Required) - The type of update. Valid values are `"OPPORTUNISTIC"`, `"PROACTIVE"`
*`max_surge_fixed` - (Optional), The maximum number of instances that can be created above the specified targetSize during the update process. Conflicts with `max_surge_percent`. If neither is set, defaults to 1
*`max_surge_percent` - (Optional), The maximum number of instances(calculated as percentage) that can be created above the specified targetSize during the update process. Conflicts with `max_surge_fixed`.
*`max_unavailable_fixed` - (Optional), The maximum number of instances that can be unavailable during the update process. Conflicts with `max_unavailable_percent`. If neither is set, defaults to 1
*`max_unavailable_percent` - (Optional), The maximum number of instances(calculated as percentage) that can be unavailable during the update process. Conflicts with `max_unavailable_fixed`.
*`min_ready_sec` - (Optional), Minimum number of seconds to wait for after a newly created instance becomes available. This value must be from range [0, 3600]
- - -
The **named_port** block supports: (Include a `named_port` block for each named-port required).