rIGM rolling update

Author: ishashchuk

docs/r/compute_region_instance_group_manager.html.markdown

@@ -87,6 +87,12 @@ The following arguments are supported:
 * `project` - (Optional) The ID of the project in which the resource belongs. If it
     is not provided, the provider project is used.
 
+* `update_strategy` - (Optional, Default `"NONE"`) If the `instance_template`
+    resource is modified, a value of `"NONE"` will prevent any of the managed
+    instances from being restarted by Terraform. A value of `"ROLLING_UPDATE"` 
+    is supported as [Beta feature]. A value of `"ROLLING_UPDATE"` requires 
+    `rolling_update_policy` block to be set
+
 * `target_size` - (Optional) The target number of running instances for this managed
     instance group. This value should always be explicitly set unless this resource is attached to
      an autoscaler, in which case it should never be set. Defaults to `0`.
@@ -104,17 +110,46 @@ The following arguments are supported:
 * `auto_healing_policies` - (Optional, [Beta](/docs/providers/google/index.html#beta-features)) The autohealing policies for this managed instance
 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).
 
+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"`
 
-The `named_port` block supports: (Include a `named_port` block for each named-port required).
+* `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]
+- - -
+
+The **named_port** block supports: (Include a `named_port` block for each named-port required).
 
 * `name` - (Required) The name of the port.
 
 * `port` - (Required) The port number.
+- - -
 
-The `auto_healing_policies` block supports:
+The **auto_healing_policies** block supports:
 
 * `health_check` - (Required) The health check resource that signals autohealing.