The Google Compute Engine Regional Instance Group Manager API creates and manages pools
of homogeneous Compute Engine virtual machine instances from a common instance
template. For more information, see [the official documentation](https://cloud.google.com/compute/docs/instance-groups/distributing-instances-with-regional-instance-groups)
and [API](https://cloud.google.com/compute/docs/reference/latest/regionInstanceGroupManagers)
~> **Note:** Use [google_compute_instance_group_manager](/docs/providers/google/r/compute_instance_group_manager.html) to create a single-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/regionInstanceGroupManagers/patch)
*`distribution_policy_zones` - (Optional, [Beta](/docs/providers/google/index.html#beta-features)) The distribution policy for this managed instance
group. You can specify one or more values. For more information, see the [official documentation](https://cloud.google.com/compute/docs/instance-groups/distributing-instances-with-regional-instance-groups#selectingzones).
*`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`. It has to be either 0 or at least equal to the number of zones. If fixed values are used, at least one of `max_unavailable_fixed` or `max_surge_fixed` must be greater than 0.
*`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`. Percent value is only allowed for regional managed instance groups with size at least 10.
*`max_unavailable_fixed` - (Optional), The maximum number of instances that can be unavailable during the update process. Conflicts with `max_unavailable_percent`. It has to be either 0 or at least equal to the number of zones. If fixed values are used, at least one of `max_unavailable_fixed` or `max_surge_fixed` must be greater than 0.
*`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`. Percent value is only allowed for regional managed instance groups with size at least 10.
*`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]
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The **named_port** block supports: (Include a `named_port` block for each named-port required).