---
layout: "google"
page_title: "Google: google_compute_instance_group_manager"
sidebar_current: "docs-google-compute-instance-group-manager"
description: |-
  Manages an Instance Group within GCE.
---

# google\_compute\_instance\_group\_manager

The Google Compute Engine 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/manager)
and [API](https://cloud.google.com/compute/docs/instance-groups/manager/v1beta2/instanceGroupManagers)

## Example Usage

```hcl
resource "google_compute_instance_group_manager" "foobar" {
  name        = "terraform-test"
  description = "Terraform test instance group manager"

  base_instance_name = "foobar"
  instance_template  = "${google_compute_instance_template.foobar.self_link}"
  update_strategy    = "NONE"
  zone               = "us-central1-a"

  target_pools = ["${google_compute_target_pool.foobar.self_link}"]
  target_size  = 2

  named_port {
    name = "customHTTP"
    port = 8888
  }
}
```

## Argument Reference

The following arguments are supported:

* `base_instance_name` - (Required) The base instance name to use for
    instances in this group. The value must be a valid
    [RFC1035](https://www.ietf.org/rfc/rfc1035.txt) name. Supported characters
    are lowercase letters, numbers, and hyphens (-). Instances are named by
    appending a hyphen and a random four-character string to the base instance
    name.

* `instance_template` - (Required) The full URL to an instance template from
    which all new instances will be created.

* `name` - (Required) The name of the instance group manager. Must be 1-63
    characters long and comply with
    [RFC1035](https://www.ietf.org/rfc/rfc1035.txt). Supported characters
    include lowercase letters, numbers, and hyphens.

* `zone` - (Required) The zone that instances in this group should be created
    in.

- - -

* `description` - (Optional) An optional textual description of the instance
    group manager.

* `named_port` - (Optional) The named port configuration. See the section below
    for details on configuration.

* `project` - (Optional) The project in which the resource belongs. If it
    is not provided, the provider project is used.

* `update_strategy` - (Optional, Default `"RESTART"`) 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 `"RESTART"` will
    restart all of the instances at once. In the future, as the GCE API matures
    we will support `"ROLLING_UPDATE"` as well.

* `target_size` - (Optional) If not given at creation time, this defaults to 1.
    Do not specify this if you are managing the group with an autoscaler, as
    this will cause fighting.

* `target_pools` - (Optional) The full URL of all target pools to which new
    instances in the group are added. Updating the target pools attribute does
    not affect existing instances.

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.

## Attributes Reference

In addition to the arguments listed above, the following computed attributes are
exported:

* `fingerprint` - The fingerprint of the instance group manager.

* `instance_group` - The full URL of the instance group created by the manager.

* `self_link` - The URL of the created resource.