Console

1. Go to theInstance groups page.

   Go to Instance groups

   The remaining steps appear in the Google Cloud console.

2. ClickCreate instance group.
3. Select theNew managed instance group (stateful) option.
4. Assign a name and optionally a description to your instance group.
5. Choose an instance template for the instance group orcreate a new one.
6. In theNumber of instances field, specify the initial number of VMs you need in this group.
7. In theStateful configuration section, underGroup config, click the disk you want to make stateful, then perform the following steps.
1. In theStateful section, selectYes.
2. In theOn permanent instance deletion list, choose whether you want to detach the disk or delete the disk when you permanently delete the VM.
3. To save the settings, clickDone.
8. To create the MIG, clickCreate.

gcloud

To specify which disks from the instance template should be stateful on MIGcreation, use the--stateful-disk flag with thegcloud compute instance-groups managed create command:

gcloud compute instance-groups managed createINSTANCE_GROUP_NAME \    --templateINSTANCE_TEMPLATE_URL \    --sizeSIZE \    --stateful-disk device-name=DEVICE_NAME[,auto-delete=DELETE_RULE]

Replace the following:

• INSTANCE_GROUP_NAME: The name of the managedinstance group to create.
• INSTANCE_TEMPLATE_URL: the URL of the instance template that you want touse to create VMs in the MIG. The URL can contain either theIDor name of the instance template. Specify one of the following values:
  • For a regional instance template:projects/PROJECT_ID/regions/REGION/instanceTemplates/INSTANCE_TEMPLATE_ID
  • For a global instance template:INSTANCE_TEMPLATE_ID
• SIZE: The initial number of VMs you needin this group.
• DEVICE_NAME: The device name of adisk specified in the instance template.

• DELETE_RULE: A value that prescribeswhat should happen to a stateful disk when a VM is deleted. Availableoptions are:

  • never: (Default.) Never delete the disk; instead, detach thedisk when its VM is deleted.
  • on-permanent-instance-deletion: Delete the disk whenits VM instance is permanentlydeleted from the instance group, forexample, when the managed instance is deleted manually or when thegroup size is decreased.

  Regardless of the value of the delete rule, stateful disks are alwayspreserved on VM autohealing, update, and recreation operations.

Terraform

If you haven't already created an instance template, which specifies themachine type, boot disk image, network, and other VM properties that youwant for each VM in your MIG,create an instance template.

To specify which disks from the instance template should be stateful on MIGcreation, include thestateful_disk block. The following sample creates azonal MIG with stateful disks. For more information about the resource thatis used in the sample, seegoogle_compute_instance_group_managerresource.

resource "google_compute_instance_group_manager" "default" {  name               = "igm-stateful-disk-basic"  zone               = "us-central1-f"  base_instance_name = "instance"  target_size        = 1  version {    instance_template = google_compute_instance_template.default.id  }  stateful_disk {    device_name = "example-disk"    delete_rule = "NEVER"  }}

To learn how to apply or remove a Terraform configuration, seeBasic Terraform commands.

REST

To specify which disks from the instance template should be stateful on MIGcreation, include them in thestatefulPolicy field in your request body.For a zonal MIG, use theinstanceGroupManagers.insert methodor for a regional MIG, use theregionInstanceGroupManagers.insert method.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT/zones/ZONE/instanceGroupManagers{  "name": "NAME",  "versions": [    {      "instanceTemplate": "INSTANCE_TEMPLATE_URL"    }  ],  "targetSize":SIZE,  "statefulPolicy": {    "preservedState": {      "disks": {        "DEVICE_NAME": {"autoDelete": "DELETE_RULE" },        "DEVICE_NAME": {"autoDelete": "DELETE_RULE" }      }    }  }}

Replace the following:

• PROJECT: The project ID for the request.
• ZONE: Thezone where the MIG is located(applies to a zonal MIG).
  • For a regional MIG, replacezones/ZONE withregions/REGION and specify the region ofthe MIG.
• NAME: The name of the MIG tocreate.
• INSTANCE_TEMPLATE_URL: the URL of the instance template that you want touse to create VMs in the MIG. The URL can contain either theIDor name of the instance template. Specify one of the following values:
  • For a regional instance template:projects/PROJECT_ID/regions/REGION/instanceTemplates/INSTANCE_TEMPLATE_ID
  • For a global instance template:INSTANCE_TEMPLATE_ID
• SIZE: The initial number of instances you needin this group.
• DEVICE_NAME: The device name of adisk specified in the instance template.

• DELETE_RULE: A value that prescribeswhat should happen to the stateful disk when the VM instance is deleted.The available options are:

  • never: (Default.) Never delete the disk; detach the disk whenthe VM is deleted.
  • on_permanent_instance_deletion: Delete the stateful disk whenits VM is permanentlydeleted from the instance group, for example, when the managed instance isdeleted manually or when the group size is decreased.

  Regardless of the value of the delete rule, stateful disks arealways preserved on instance autohealing, update, and recreationoperations.