Manage Compute Engine resources using custom constraints

Google Cloud Organization Policy gives you centralized, programmatic control over your organization's resources. As the organization policy administrator, you can define an organization policy, which is a set of restrictions called constraints that apply to Google Cloud resources and descendants of those resources in the Google Cloud resource hierarchy. You can enforce organization policies at the organization, folder, or project level.

Organization Policy provides predefined constraints for various Google Cloud services. However, if you want more granular, customizable control over the specific fields that are restricted in your organization policies, you can also create custom constraints and use those custom constraints in a custom organization policy.

Benefits

Cost management: use custom organization policies to restrict the VM instance and disk sizes and types that can be used in your organization. You can also restrict the machine family that is used for the VM instance
Security, compliance, and governance: you can use custom organization policies to enforce policies as follows:
- To enforce security requirements, you can require specific firewall port rules on VMs.
- To support hardware isolation or licensing compliance, you can require all VMs within a specific project or folder to run on sole-tenant nodes.
- To govern automation scripts, you can use custom organization policies to verify labels match desired expressions.

Policy inheritance

By default, organization policies are inherited by the descendants of the resources on which you enforce the policy. For example, if you enforce a policy on a folder, Google Cloud enforces the policy on all projects in the folder. To learn more about this behavior and how to change it, refer to Hierarchy evaluation rules.

Pricing

The Organization Policy Service, including predefined and custom organization policies, is offered at no charge.

Limitations

Currently, custom organization policies are only enforced on the CREATE method for Compute Engine resources.

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:
Console

When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.
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.

Ensure that you know your organization ID.

Required roles

To get the permissions that you need to manage organization policies for Compute Engine resources, ask your administrator to grant you the following IAM roles:

Organization policy administrator (roles/orgpolicy.policyAdmin) on the organization resource
To test the constraints: Compute Instance Admin (v1) (roles/compute.instanceAdmin.v1) on the project

For more information about granting roles, see Manage access.

These predefined roles contain the permissions required to manage organization policies for Compute Engine resources. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to manage organization policies for Compute Engine resources:

orgpolicy.constraints.list
orgpolicy.policies.create
orgpolicy.policies.delete
orgpolicy.policies.list
orgpolicy.policies.update
orgpolicy.policy.get
orgpolicy.policy.set
To test the constraints:
- compute.instances.create on the project
- To use a custom image to create the VM: compute.images.useReadOnly on the image
- To use a snapshot to create the VM: compute.snapshots.useReadOnly on the snapshot
- To use an instance template to create the VM: compute.instanceTemplates.useReadOnly on the instance template
- To assign a legacy network to the VM: compute.networks.use on the project
- To specify a static IP address for the VM: compute.addresses.use on the project
- To assign an external IP address to the VM when using a legacy network: compute.networks.useExternalIp on the project
- To specify a subnet for the VM: compute.subnetworks.use on the project or on the chosen subnet
- To assign an external IP address to the VM when using a VPC network: compute.subnetworks.useExternalIp on the project or on the chosen subnet
- To set VM instance metadata for the VM: compute.instances.setMetadata on the project
- To set tags for the VM: compute.instances.setTags on the VM
- To set labels for the VM: compute.instances.setLabels on the VM
- To set a service account for the VM to use: compute.instances.setServiceAccount on the VM
- To create a new disk for the VM: compute.disks.create on the project
- To attach an existing disk in read-only or read-write mode: compute.disks.use on the disk
- To attach an existing disk in read-only mode: compute.disks.useReadOnly on the disk

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

Compute Engine supported resources

For Compute Engine, you can set custom constraints on the following resources and fields.

Persistent Disk: compute.googleapis.com/Disk
- Persistent Disk type: resource.type
- Persistent Disk size: resource.sizeGb
Image: compute.googleapis.com/Image
- Raw disk source: resource.rawDisk.source
VM instance: compute.googleapis.com/Instance
- Labels: resource.labels
- Machine type: resource.machineType
- Network interface:
  - resource.networkInterfaces.network
  - resource.networkInterfaces.subnetwork
- Node affinity:
  - resource.scheduling.nodeAffinities.key
  - resource.scheduling.nodeAffinities.operator
  - resource.scheduling.nodeAffinities.values

Set up a custom constraint

A custom constraint is defined by the resources, methods, conditions, and actions that are supported by the service on which you are enforcing the organization policy. Conditions for your custom constraints are defined using Common Expression Language (CEL). For more information about how to build conditions in custom constraints using CEL, see the CEL section of Creating and managing custom organization policies.

You can create a custom constraint and set it up for use in organization policies using the Google Cloud console or Google Cloud CLI.

Console

In the Google Cloud console, go to the Organization policies page.

Go to Organization policies
Select the Project picker at the top of the page.
From the Project picker, select the resource for which you want to set the organization policy.
Click Custom constraint.
In the Display name box, enter a human-friendly name for the constraint. This field has a maximum length of 200 characters. Don't use PII or sensitive data in constraint names, because they could be exposed in error messages.
In the Constraint ID box, enter the name you want for your new custom constraint. A custom constraint must start with custom., and can only include uppercase letters, lowercase letters, or numbers, for example, custom.createOnlyN2DVMs. The maximum length of this field is 70 characters, not counting the prefix, for example, organizations/123456789/customConstraints/custom..
In the Description box, enter a human-friendly description of the constraint to display as an error message when the policy is violated. This field has a maximum length of 2000 characters.
In the Resource type box, select the name of the Google Cloud REST resource containing the object and field you want to restrict. For example, compute.googleapis.com/Instance.
Under Enforcement method, select whether to enforce the constraint on the REST CREATE method.
To define a condition, click Edit condition.
1. In the Add condition panel, create a CEL condition that refers to a supported service resource, for example resource.machineType.contains('/machineTypes/n2d'). This field has a maximum length of 1000 characters.
2. Click Save.
Under Action, select whether to allow or deny the evaluated method if the above condition is met.
Click Create constraint.

When you have entered a value into each field, the equivalent YAML configuration for this custom constraint appears on the right.

gcloud

To create a custom constraint using the Google Cloud CLI, create a YAML file for the custom constraint:

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resource_types: compute.googleapis.com/RESOURCE_NAME
method_types: CREATE
condition: CONDITION
action_type: ACTION
display_name: DISPLAY_NAME
description: DESCRIPTION

Replace the following:

ORGANIZATION_ID: your organization ID, such as 123456789.
CONSTRAINT_NAME: the name you want for your new custom constraint. A custom constraint must start with custom., and can only include uppercase letters, lowercase letters, or numbers. For example, custom.createOnlyN2DVMs. The maximum length of this field is 70 characters, not counting the prefix (for example, organizations/123456789/customConstraints/custom.).
RESOURCE_NAME: the name (not the URI) of the Compute Engine API REST resource containing the object and field you want to restrict. For example, Instance.
CONDITION: a CEL condition that is written against a representation of a supported service resource. This field has a maximum length of 1000 characters. See Supported resources for more information about the resources available to write conditions against. For example, "resource.machineType.contains('/machineTypes/n2d')".
ACTION: the action to take if the condition is met. This can be either ALLOW or DENY.
DISPLAY_NAME: a human-friendly name for the constraint. This field has a maximum length of 200 characters.
DESCRIPTION: a human-friendly description of the constraint to display as an error message when the policy is violated. This field has a maximum length of 2000 characters.

For more information about how to create a custom constraint, see Creating and managing custom organization policies.

After you have created a new custom constraint using the Google Cloud CLI, you must set it up to make it available for organization policies in your organization. To set up a custom constraint, use the gcloud org-policies set-custom-constraint command:

gcloud org-policies set-custom-constraint CONSTRAINT_PATH

Replace CONSTRAINT_PATH with the full path to your custom constraint file. For example, /home/user/customconstraint.yaml. Once completed, you will find your custom constraints as available organization policies in your list of Google Cloud organization policies. To verify that the custom constraint exists, use the gcloud org-policies list-custom-constraints command:

gcloud org-policies list-custom-constraints --organization=ORGANIZATION_ID

Replace ORGANIZATION_ID with the ID of your organization resource. For more information, see Viewing organization policies.

Enforce a custom constraint

You can enforce a boolean constraint by creating an organization policy that references it, and applying that organization policy to a Google Cloud resource.

Console

To enforce a boolean constraint:

In the Google Cloud console, go to the Organization policies page.
Go to Organization policies
Select the project picker at the top of the page.
From the project picker, select the project for which you want to set the organization policy.
Select your constraint from the list on the Organization policies page. The Policy details page for that constraint should appear.
To configure the organization policy for this resource, click Manage policy.
On the Edit policy page, select Override parent's policy.
Click Add a rule.
Under Enforcement, select whether enforcement of this organization policy should be on or off.
Optionally, to make the organization policy conditional on a tag, click Add condition. Note that if you add a conditional rule to an organization policy, you must add at least one unconditional rule or the policy cannot be saved. For more details, see Setting an organization policy with tags.
If this is a custom constraint, you can click Test changes to simulate the effect of this organization policy. For more information, see Test organization policy changes with Policy Simulator.
To finish and apply the organization policy, click Set policy. The policy will take up to 15 minutes to take effect.

gcloud

To create an organization policy that enforces a boolean constraint, create a policy YAML file that references the constraint:

      name: projects/PROJECT_ID/policies/CONSTRAINT_NAME
      spec:
        rules:
        - enforce: true

Replace the following:

PROJECT_ID: the project on which you want to enforce your constraint.
CONSTRAINT_NAME: the name you defined for your custom constraint. For example, custom.createOnlyN2DVMs.

To enforce the organization policy containing the constraint, run the following command:

    gcloud org-policies set-policy POLICY_PATH

Replace POLICY_PATH with the full path to your organization policy YAML file. The policy will take up to 15 minutes to take effect.

Example: Create a constraint that restrict VMs to use the N2D machine type

gcloud

Create a onlyN2DVMs.yaml constraint file with the following information:

name: organizations/ORGANIZATION_ID/customConstraints/custom.createOnlyN2DVMs
resource_types: compute.googleapis.com/Instance
condition: "resource.machineType.contains('/machineTypes/n2d')"
action_type: ALLOW
method_types: CREATE
display_name: Only N2D VMs allowed
description: Restrict all VMs created to only use N2D machine types.

Set the custom constraint.

gcloud org-policies set-custom-constraint onlyN2DVMs.yaml

Create a onlyN2DVMs-policy.yaml policy file with the following information. In this example we enforce this constraint at the project level but you might also set this at the organization or folder level. Replace PROJECT_ID with your project ID.
```
name: projects/PROJECT_ID/policies/custom.createOnlyN2DVMs
spec:
  rules:
  – enforce: true
```

Enforce the policy.

gcloud org-policies set-policy onlyN2DVMs-policy.yaml

Test the constraint by trying to create a VM that uses a machine type that isn't an N2D machine.

gcloud compute instances create my-test-instance \
    --project=PROJECT_ID \
    --zone=us-central1-c \
    --machine-type=e2-medium

The output is similar to the following:

ERROR: (gcloud.compute.instances.create) Could not fetch resource:
– Operation denied by custom org policies: [customConstraints/custom.createOnlyN2DVMs]: Restrict all VMs created to only use N2D machine types.

Example custom constraints for common use cases

The following sections provide the syntax of some custom constraints that you might find useful:

Disk

Use case Syntax

Use case	Syntax
Persistent Disk type must be "Extreme persistent disk (`pd-extreme`)"	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createDisksPDExtremeOnly resource_types: compute.googleapis.com/Disk condition: "resource.type.contains('pd-extreme')" action_type: ALLOW method_types: CREATE display_name: Create pd-extreme disks only description: Only the extreme persistent disk type is allowed to be created.
Disk size must be less than or equal to 250 GB	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createDisksLessThan250GB resource_types: compute.googleapis.com/Disk condition: "resource.sizeGb <= 250" action_type: ALLOW method_types: CREATE display_name: Disks size maximum is 250 GB description: Restrict the boot disk size to 250 GB or less for all VMs.

Persistent Disk type must be "Extreme persistent disk (pd-extreme)"

  name: organizations/ORGANIZATION_ID/customConstraints/custom.createDisksPDExtremeOnly
  resource_types: compute.googleapis.com/Disk
  condition: "resource.type.contains('pd-extreme')"
  action_type: ALLOW
  method_types: CREATE
  display_name: Create pd-extreme disks only
  description: Only the extreme persistent disk type is allowed to be created.

Disk size must be less than or equal to 250 GB

  name: organizations/ORGANIZATION_ID/customConstraints/custom.createDisksLessThan250GB
  resource_types: compute.googleapis.com/Disk
  condition: "resource.sizeGb <= 250"
  action_type: ALLOW
  method_types: CREATE
  display_name: Disks size maximum is 250 GB
  description: Restrict the boot disk size to 250 GB or less for all VMs.

Image

Use case Syntax

Use case	Syntax
Source images must be from Cloud Storage `test_bucket` only	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createDisksfromStoragebucket resource_types: compute.googleapis.com/Image condition: "resource.rawDisk.source.contains('storage.googleapis.com/test_bucket/')" action_type: ALLOW method_types: CREATE display_name: Source image must be from Cloud Storage test_bucket only description: Source images used in this project must be imported from the Cloud Storage test_bucket.

Source images must be from Cloud Storage test_bucket only

  name: organizations/ORGANIZATION_ID/customConstraints/custom.createDisksfromStoragebucket
  resource_types: compute.googleapis.com/Image
  condition: "resource.rawDisk.source.contains('storage.googleapis.com/test_bucket/')"
  action_type: ALLOW
  method_types: CREATE
  display_name: Source image must be from Cloud Storage test_bucket only
  description: Source images used in this project must be imported from the
  Cloud Storage test_bucket.

VM instance

Use case	Syntax
VM must have a label with the key set to `cost center`	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createVMWithLabel resource_types: compute.googleapis.com/Instance condition: "'cost_center' in resource.labels" action_type: ALLOW method_types: CREATE display_name: 'cost_center' label required description: Requires that all VMs created must have the a 'cost_center' label that can be used for tracking and billing purposes.
VM must have a label with the key set to `cost center` and the value set to `eCommerce`	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createECommerceVMOnly resource_types: compute.googleapis.com/Instance condition: "'cost_center' in resource.labels and resource.labels['cost_center'] == 'eCommerce'" action_type: ALLOW method_types: CREATE display_name: Label (cost_center/eCommerce) required description: Label required and Key/value must be cost_center/eCommerce.
VM must use machine type N2D	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createOnlyN2DVMs resource_types: compute.googleapis.com/Instance condition: "resource.machineType.contains('/machineTypes/n2d')" action_type: ALLOW method_types: CREATE display_name: Only N2D VMs allowed description: Restrict all VMs created to only use N2D machine types.
VM must use machine type `e2-highmem-8`	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createOnlyE2highmem8 resource_types: compute.googleapis.com/Instance condition: "resource.machineType.endsWith('-e2-highmem-8')" action_type: ALLOW method_types: CREATE display_name: Only "e2-highmem-8" VMs allowed description: Restrict all VMs created to only use the E2 high-memory machine types that have 8 vCPUs.
Ensures that VMs are scheduled on the node group "foo"	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.createOnlySTVM resource_types: compute.googleapis.com/Instance condition: "resource.scheduling.nodeAffinities.exists(n, n.key == 'foo')" action_type: ALLOW method_types: CREATE display_name: Only VMs scheduled on node group "foo" allowed description: Restrict all VMs created to use the node group "foo".

What's next

See Introduction to the Organization Policy Service to learn more about organization policies.
Learn more about how to create and manage organization policies.
See the full list of predefined Organization policy constraints.