Create and apply spread placement policies to VMs

This document explains how to create a spread placement policy and apply it to one or more virtual machine (VM) instances for improved reliability.

A spread placement policy specifies that your VMs should be physically placed far apart from each other by placing them in different availability domains. Use a spread placement policy to ensure that your VMs are placed on distinct hardware, reducing the impact of underlying hardware failures or optimizing live migration.

You can apply a spread placement policy when you do the following:

Create or update a VM.
Create VMs in bulk.
Create an instance template. The instance template then applies the spread placement policy when you use it to do the following:
- Create a VM.
- Create or update a managed instance group (MIG).

Before you begin

If you haven't already, set up authentication. Authentication is the process by which your identity is verified for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine as follows.

Select the tab for how you plan to use the samples on this page:
gcloud
1. Install the Google Cloud CLI, then initialize it by running the following command:
```
gcloud init
```
  Note: If you installed the gcloud CLI previously, make sure you have the latest version by running gcloud components update.
2. Set a default region and zone.
REST

To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

Required roles

To get the permissions that you need to create and apply a spread placement policy to VMs, ask your administrator to grant you the Compute Instance Admin (v1) (roles/compute.instanceAdmin.v1) IAM role on the VM or the project. For more information about granting roles, see Manage access.

This predefined role contains the permissions required to create and apply a spread placement policy to VMs. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to create and apply a spread placement policy to VMs:

To create placement policies: compute.resourcePolicies.create on the project
To apply a placement policy to an existing VM: compute.instances.addResourcePolicies on the project

You might also be able to get these permissions with custom roles or other predefined roles.

Restrictions

In addition to the general restrictions for placement policies, spread placement policies have the following restrictions:

You can only apply a spread placement policy to 8 VMs maximum.
You can't apply spread placement policies to reservations of VMs.
You can't verify the physical location of VMs.

Create a spread placement policy

You can create a spread placement policy using the gcloud CLI and REST.

gcloud

To create a spread placement policy, use the gcloud compute resource-policies create group-placement command with the --availability-domain-count flag.

gcloud compute resource-policies create group-placement POLICY_NAME \
    --availability-domain-count=DOMAIN_COUNT \
    --region=REGION

Replace the following:

POLICY_NAME: the name of the spread placement policy to create.
DOMAIN_COUNT: the distinct number of availability domains to place your VMs in. Each domain has its own independent power, cooling, and networking source. The value must be between 2 and 8, which is the maximum number of VMs you can apply a spread placement policy to.
REGION: the region where to create the policy.

REST

To create a spread placement policy, make a POST request to the resourcePolicies.insert method. In the request body, include the availabilityDomainCount field.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/resourcePolicies

{
  "name": "POLICY_NAME",
  "groupPlacementPolicy": {
    "availabilityDomainCount": DOMAIN_COUNT
  }
}

Replace the following:

PROJECT_ID: the ID of the project where you want to create the policy.
REGION: the region where you want to create the policy.
POLICY_NAME: the name of the spread placement policy to create.
DOMAIN_COUNT: the distinct number of availability domains to place your VMs in. Each domain has its own independent power, cooling, and networking source. The value must be between 2 and 8, which is the maximum number of VMs you can apply a spread placement policy to.

Apply spread placement policies

You can apply a spread placement policy to an existing VM, or when you create VMs, instance templates, or MIGs.

To create a Compute Engine resource that specifies a spread placement policy, or apply the spread placement policy to an existing VM, select one of the following methods:

Apply a spread placement policy to an existing VM.
Create a VM that specifies a spread placement policy.
Create VMs in bulk that specify a spread placement policy.
Create an instance template that specifies a spread placement policy.
Apply a spread placement policy to the VMs in a MIG.

Apply a spread placement policy to an existing VM

You can apply a spread placement policy to an existing VM using the gcloud CLI and REST.

gcloud

To apply a spread placement policy to an existing VM, use the gcloud compute instances add-resource-policies command with the --resource-policies flag.

gcloud compute instances add-resource-policies VM_NAME \
    --resource-policies=POLICY_NAME \
    --zone=ZONE

Replace the following:

VM_NAME: the name of an existing VM.
POLICY_NAME: the name of an existing spread placement policy.
ZONE: the zone where the VM exists, which must be within the region where the spread placement policy is located.

REST

To apply a spread placement policy to an existing VM, make a POST request to the instances.addResourcePolicies method. In the request body, include the resourcePolicies field.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME/addResourcePolicies

{
  "resourcePolicies": [
    "projects/PROJECT_ID/regions/REGION/resourcePolicies/POLICY_NAME"
  ]
}

Replace the following:

PROJECT_ID: the ID of the project where the spread placement policy and the VM are located.
ZONE: the zone where the VM exists, which must be within the region where the spread placement policy is located.
VM_NAME: the name of an existing VM.
REGION: the region where the spread placement policy is located.
POLICY_NAME: the name of an existing spread placement policy.

Create a VM that specifies a spread placement policy

You can create a VM that specifies an existing spread placement policy using the gcloud CLI and REST.

gcloud

To create a VM that specifies a spread placement policy, use the gcloud compute instances create command with the --resource-policies flag.

For example, to create a VM that has default properties and specifies a spread placement policy, run the following command:

gcloud compute instances create VM_NAME \
    --resource-policies=POLICY_NAME \
    --zone=ZONE

Replace the following:

VM_NAME: the name of the VM to create.
POLICY_NAME: the name of an existing spread placement policy.
ZONE: the zone where to create the VM. You can only create a VM in a zone that is within the region where the spread placement policy you specify is located.

REST

To create a VM that specifies a spread placement policy, make a POST request to the instances.insert method. In the request body, include the resourcePolicies field.

For example, to create a VM that has default properties and specifies a spread placement policy, make the following POST request:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances

{
  "name": "VM_NAME",
  "resourcePolicies": [
    "projects/PROJECT_ID/regions/REGION/resourcePolicies/POLICY_NAME"
  ]
}

Replace the following:

PROJECT_ID: the ID of the project where the spread placement policy is located.
ZONE: the zone where to create the VM. You can only create a VM in a zone that is within the region where the spread placement policy you specify is located.
VM_NAME: the name of the VM to create.
REGION: the region where the spread placement policy is located.
POLICY_NAME: the name of an existing spread placement policy.

For more information about the configuration options and the IAM roles to create a VM, see Create and start a VM instance.

Create VMs in bulk that specify a spread placement policy

You can create VMs in bulk that specify an existing spread placement policy using the gcloud CLI and REST.

gcloud

To create VMs in bulk that specify a spread placement policy, use the gcloud compute instances bulk create command with the --async and --resource-policies flags.

For example, to create VMs in bulk that all have default properties and specify the same spread placement policy, run the following command:

gcloud compute instances bulk create \
    --async \
    --count=COUNT \
    --name-pattern=NAME_PATTERN \
    --resource-policies=POLICY_NAME \
    --zone=ZONE

Replace the following:

COUNT: the number of VMs to create.
NAME_PATTERN: the name pattern for the VMs to create. Use the hash character (#) to replace it with a sequence of numbers. For example, specifying vm-# creates VMs with names vm-1, vm-2, and so on, up to the number of VMs specified in COUNT.
POLICY_NAME: the name of an existing spread placement policy.
ZONE: the zone where to bulk create the VMs. You can only create VMs in zones that are within the region of the spread placement policy you specify.

REST

To create VMs in bulk that specify a spread placement policy, make a POST to the instances.bulkInsert method. In the request body, include the resourcePolicies field.

For example, to create VMs in bulk that all have default properties and specify the same spread placement policy, make the following POST request:

POST https://www.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/bulkInsert

{
  "count": "COUNT",
  "namePattern": "NAME_PATTERN",
  "instanceProperties": {
    "resourcePolicies": [
      "projects/PROJECT_ID/regions/REGION/resourcePolicies/POLICY_NAME"
    ]
  }
}

Replace the following:

PROJECT_ID: the ID of the project where the spread placement policy is located.
ZONE: the zone where to bulk create the VMs. You can only create VMs in zones that are within the region of the spread placement policy you specify.
COUNT: the number of VMs to create.
NAME_PATTERN: the name pattern for the VMs to create. Use the hash character (#) to replace it with a sequence of numbers. For example, specifying vm-# for creates VMs with names vm-1, vm-2, and so on, up to the number of VMs specified in COUNT.
REGION: the region where the spread placement policy is located.
POLICY_NAME: the name of an existing spread placement policy.

For more information about the configuration options or the IAM roles to create VMs in bulk, see Create VMs in bulk.

Create an instance template that specifies a spread placement policy

You can create an instance template that specifies an existing spread placement policy using the gcloud CLI and REST.

After you create an instance template, you can use it to do the following:

gcloud

To create an instance template that specifies a spread placement policy, use the gcloud compute instance-templates create command with --resource-policies flag.

For example, to create a global instance template that has default VM properties and includes a spread placement policy, run the following command:

gcloud compute instance-templates create INSTANCE_TEMPLATE_NAME \
    --resource-policies=POLICY_NAME

Replace the following:

INSTANCE_TEMPLATE_NAME: the name of the instance template.
PROJECT_ID: the ID of the project where the spread placement policy you want to apply to the instance template is located.
POLICY_NAME: the name of an existing spread placement policy.

REST

To create an instance template that specifies a spread placement policy, make a POST request to the instanceTemplates.insert method. In the request body, include the resourcePolicies field.

For example, to create a global instance template that has default VM properties and specifies a spread placement policy, make the following POST request:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/instanceTemplates

{
  "name": "INSTANCE_TEMPLATE_NAME",
  "properties": {
    "resourcePolicies": {
      "POLICY_NAME"
    }
  }
}

Replace the following:

PROJECT_ID: the ID of the project where the instance template you want to apply the spread placement policy to is located.
INSTANCE_TEMPLATE_NAME: the name of the instance template.
POLICY_NAME: the name of an existing spread placement policy.

For more information about the configuration options to create an instance template, see Create instance templates.

Apply a spread placement policy to the VMs in a MIG

After you create an instance template that specifies a spread placement policy, you can use the template to do the following:

Create a MIG that specifies the same spread placement policy.
Apply the spread placement policy to an existing MIG.

If you want to apply a spread placement policy to a MIG, creating or applying the policy to a regional MIG with the any single zone distribution shape is recommended. This way, whenever a regional MIG needs to scale out by creating VMs, it selects the zone where to create the VMs based on your quotas and hardware requirements.

Create a MIG that specifies a spread placement policy

You can create a MIG using an instance template that specifies a spread placement policy using the gcloud CLI and REST.

gcloud

To create a MIG using an instance template that specifies a spread placement policy, use the gcloud compute instance-groups managed create command with the --template flag set to the name of the existing template.

For example, to create a regional MIG with default VM properties and the any-single-zone distribution shape, run the following command:

gcloud compute instance-groups managed create MIG_NAME \
    --region=REGION \
    --size=SIZE \
    --target-distribution-shape=any-single-zone \
    --template=INSTANCE_TEMPLATE_NAME

Replace the following:

MIG_NAME: the name of the MIG to create.
REGION: the region where to create the MIG, which must match with the region where the spread placement policy is located.
SIZE: the size of the MIG.
INSTANCE_TEMPLATE_NAME: the name of an existing instance template that specifies a spread placement policy.

REST

To create a MIG using an instance template that specifies a spread placement policy, make a POST request to the instanceGroupManagers.insert or regionInstanceGroupManagers.insert methods. In the request body, include the instanceTemplate field and set it to the name of the existing template.

For example, to create a regional MIG with default VM properties and the any-single-zone distribution shape, make the following POST request:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/instanceGroupManagers

{
  "name": "MIG_NAME",
  "instanceTemplate": "global/instanceTemplates/INSTANCE_TEMPLATE_NAME",
  "targetSize": SIZE,
  "distributionPolicy": {
    "targetShape": "ANY_SINGLE_ZONE"
  }
}

Replace the following:

PROJECT_ID: the ID of the project where the spread placement policy and the instance template that specifies the placement policy are located.
REGION: the region where to create the MIG, which must match with the region where the spread placement policy is located.
MIG_NAME: the name of the MIG to create.
INSTANCE_TEMPLATE_NAME: the name of an existing instance template that specifies a spread placement policy.
SIZE: the size of the MIG.

For more information about the configuration options and the IAM roles to create MIGs, see Basic scenarios for creating MIGs.

Apply a spread placement policy to an existing MIG

You can apply a spread placement policy to an existing MIG using an instance template that specifies the same placement policy using the gcloud CLI and REST.

gcloud

To update a MIG to use an instance template that specifies a spread placement policy, use the gcloud compute instance-groups managed rolling-action start-update command.

For example, to update a regional MIG to use an instance template that specifies a spread placement policy and replace the existing VMs from the MIG with new VMs that specify the template's properties, run the following command:

gcloud compute instance-groups managed rolling-action start-update MIG_NAME \
    --region=REGION \
    --type=proactive \
    --version=template=INSTANCE_TEMPLATE_NAME

Replace the following:

MIG_NAME: the name of an existing MIG.
REGION: the region where the MIG is located. You can only apply the spread placement policy to a MIG that is in the same region.
INSTANCE_TEMPLATE_NAME: the name of an existing instance template that specifies a spread placement policy.

REST

To update a MIG to use an instance template that specifies a spread placement policy, and automatically apply the properties of the template and the placement policy to existing VMs in the MIG, make a PATCH request to the instanceGroupManagers.insert or regionInstanceGroupManagers.insert methods.

PATCH https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/instanceGroupManagers/MIG_NAME

{
  "instanceTemplate": "global/instanceTemplates/INSTANCE_TEMPLATE_NAME",
  "updatePolicy": {
    "type": "PROACTIVE"
  }
}

Replace the following:

PROJECT_ID: the ID of the project you used to create an existing MIG, the spread placement policy, and the instance template that specifies the spread placement policy.
REGION: the region where the MIG is located. You can only apply the spread placement policy to a MIG that is in the same region.
MIG_NAME: the name of an existing MIG.
INSTANCE_TEMPLATE_NAME: the name of an existing instance template that specifies a spread placement policy.

For more information about the configuration options and the IAM roles to update the VMs in a MIG, see Update and apply new configurations to VMs in a MIG.

What's next?

Learn how to view placement policies.
Learn how to replace, remove, or delete placement policies.
Learn how to do the following with a VM that specifies a placement policy:
- View the status of the VM.
- Connect to the VM.
Learn more about the live migration process during maintenance events.