---
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/reference/latest/instanceGroupManagers)

~> **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.

## Example Usage with top level instance template (`google` provider)

```hcl
resource "google_compute_health_check" "autohealing" {
  name                = "autohealing-health-check"
  check_interval_sec  = 5
  timeout_sec         = 5
  healthy_threshold   = 2
  unhealthy_threshold = 10                         # 50 seconds

  http_health_check {
    request_path = "/healthz"
    port         = "8080"
  }
}

resource "google_compute_instance_group_manager" "appserver" {
  name = "appserver-igm"

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

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

  named_port {
    name = "customHTTP"
    port = 8888
  }

  auto_healing_policies {
    health_check      = "${google_compute_health_check.autohealing.self_link}"
    initial_delay_sec = 300
  }
}
```

## Example Usage with multiple versions (`google-beta` provider)
```hcl
resource "google_compute_instance_group_manager" "appserver" {
  provider = "google-beta"
  name = "appserver-igm"

  base_instance_name = "app"
  zone               = "us-central1-a"

  target_size  = 5

  version {
    name = "appserver"
    instance_template  = "${google_compute_instance_template.appserver.self_link}"
  }

  version {
    name = "appserver-canary"
    instance_template  = "${google_compute_instance_template.appserver-canary.self_link}"
    target_size {
      fixed = 1
    }
  }
}
```

## 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, [GA](https://terraform.io/docs/providers/google/provider_versions.html)) The
  full URL to an instance template from which all new instances
  will be created. This field is only present in the `google` provider.

* `version` - (Required, [Beta](https://terraform.io/docs/providers/google/provider_versions.html)) Application versions managed by this instance group. Each
    version deals with a specific instance template, allowing canary release scenarios.
    Structure is documented below.

* `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 ID of the project in which the resource belongs. If it
    is not provided, the provider project is used.

* `update_strategy` - (Optional, Default `"REPLACE"`) 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 `"REPLACE"` will
    restart all of the instances at once. This field is only present in the
    `google` provider.

* `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`.

* `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.

* `wait_for_instances` - (Optional) Whether to wait for all instances to be created/updated before
    returning. Note that if this is set to true and the operation does not succeed, Terraform will
    continue trying until it times out.

---

* `auto_healing_policies` - (Optional, [Beta](https://terraform.io/docs/providers/google/provider_versions.html)) 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).

* `update_policy` - (Optional, [Beta](https://terraform.io/docs/providers/google/provider_versions.html)) 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 `update_policy` block supports:

```hcl
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).

* `name` - (Required) The name of the port.

* `port` - (Required) The port number.
- - -

The `auto_healing_policies` block supports:

* `health_check` - (Required) The health check resource that signals autohealing.

* `initial_delay_sec` - (Required) The number of seconds that the managed instance group waits before
 it applies autohealing policies to new instances or recently recreated instances. Between 0 and 3600.

The `version` block supports:

```hcl
version {
 name = "appserver-canary"
 instance_template = "${google_compute_instance_template.appserver-canary.self_link}"
 target_size {
   fixed = 1
 }
}
```

```hcl
version {
 name = "appserver-canary"
 instance_template = "${google_compute_instance_template.appserver-canary.self_link}"
 target_size {
   percent = 20
 }
}
```

* `name` - (Required) - Version name.

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

* `target_size` - (Optional) - The number of instances calculated as a fixed number or a percentage depending on the settings. Structure is documented below.

-> Exactly one `version` you specify must not have a `target_size` specified. During a rolling update, the instance group manager will fulfill the `target_size`
constraints of every other `version`, and any remaining instances will be provisioned with the version where `target_size` is unset.


The `target_size` block supports:

* `fixed` - (Optional), The number of instances which are managed for this version. Conflicts with `percent`.

* `percent` - (Optional), The number of instances (calculated as percentage) which are managed for this version. Conflicts with `fixed`.
Note that when using `percent`, rounding will be in favor of explicitly set `target_size` values; a managed instance group with 2 instances and 2 `version`s,
one of which has a `target_size.percent` of `60` will create 2 instances of that `version`.

## 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.


## Import

Instance group managers can be imported using the `name`, e.g.

```
$ terraform import google_compute_instance_group_manager.appserver appserver-igm
```