Custom constraints

This page shows you how to use Organization Policy Service custom constraints to restrict specific operations on the following Google Cloud resources:

• compute.googleapis.com/Disk
• compute.googleapis.com/Image
• compute.googleapis.com/Instance
• compute.googleapis.com/InstanceGroup

To learn more about Organization Policy, see Custom organization policies.

About organization policies and constraints

The Google Cloud Organization Policy Service 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 built-in managed 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 an organization policy.

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.

Benefits

• Cost management: use custom organization policies to restrict the virtual machine (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 that labels match specified expressions.

Before you begin

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Roles required to select or create a project

• Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
• Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

Go to project selector

Verify that billing is enabled for your Google Cloud project.

Install the Google Cloud CLI.

If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

To initialize the gcloud CLI, run the following command:

gcloud init

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Roles required to select or create a project

• Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
• Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

Go to project selector

Verify that billing is enabled for your Google Cloud project.

Install the Google Cloud CLI.

If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

To initialize the gcloud CLI, run the following command:

gcloud init

1. 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 to projects, folders, and organizations.

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.

Set up a custom constraint

A custom constraint is defined in a YAML file 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 constraints.

Console

To create a custom constraint, do the following:

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

   Go to Organization policies

2. From the project picker, select the project that you want to set the organization policy for.
3. Click Custom constraint.
4. In the Display name box, enter a human-readable name for the constraint. This name is used in error messages and can be used for identification and debugging. Don't use personally identifiable information (PII) or sensitive data in display names because this name could be exposed in error messages. This field can contain up to 200 characters.
5. In the Constraint ID box, enter the ID that you want for your new custom constraint. A custom constraint can only contain letters (including upper and lowercase) or numbers, for example custom.createOnlyN2DVMs. This field can contain up to 70 characters, not counting the prefix (custom.), for example, organizations/123456789/customConstraints/custom. Don't include PII or sensitive data in your constraint ID, because it could be exposed in error messages.
6. In the Description box, enter a human-readable description of the constraint. This description is used as an error message when the policy is violated. Include details about why the policy violation occurred and how to resolve the policy violation. Don't include PII or sensitive data in your description, because it could be exposed in error messages. This field can contain up to 2000 characters.
7. In the Resource type box, select the name of the Google Cloud REST resource containing the object and field that you want to restrict—for example, container.googleapis.com/NodePool. Most resource types support up to 20 custom constraints. If you attempt to create more custom constraints, the operation fails.
8. Under Enforcement method, select whether to enforce the constraint on a REST CREATE method or both CREATE and UPDATE methods. If you enforce the constraint with the UPDATE method on a resource that violates the constraint, changes to that resource are blocked by the organization policy unless the change resolves the violation.

To see supported methods for each service, find the service in Services that support custom constraints.

9. 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.management.autoUpgrade == false. This field can contain up to 1000 characters. For details about CEL usage, see Common Expression Language. For more information about the service resources you can use in your custom constraints, see Custom constraint supported services.
2. Click Save.
10. Under Action, select whether to allow or deny the evaluated method if the condition is met.

The deny action means that the operation to create or update the resource is blocked if the condition evaluates to true.

The allow action means that the operation to create or update the resource is permitted only if the condition evaluates to true. Every other case except those explicitly listed in the condition is blocked.

11. 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

1. To create a custom constraint, create a YAML file using the following format:

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resourceTypes: RESOURCE_NAME
methodTypes:
  - CREATE
  - UPDATE 
condition: "CONDITION"
actionType: ACTION
displayName: DISPLAY_NAME
description: DESCRIPTION

Replace the following:

• ORGANIZATION_ID: your organization ID, such as 123456789.
• CONSTRAINT_NAME: the name that you want for your new custom constraint. A custom constraint can only contain letters (including upper and lowercase) or numbers, for example, custom.createOnlyN2DVMs. This field can contain up to 70 characters, not counting the prefix (custom.)— for example, organizations/123456789/customConstraints/custom. Don't include PII or sensitive data in your constraint ID, because it could be exposed in error messages.
• RESOURCE_NAME: the fully qualified name of the Google Cloud resource containing the object and field that you want to restrict. For example, compute.googleapis.com/Instance. Most resource types support up to 20 custom constraints. If you attempt to create more custom constraints, the operation fails.
• methodTypes: the REST methods that the constraint is enforced on. Can be CREATE or both CREATE and UPDATE. If you enforce the constraint with the UPDATE method on a resource that violates the constraint, changes to that resource are blocked by the organization policy unless the change resolves the violation.

To see the supported methods for each service, find the service in Services that support custom constraints.

• CONDITION: a CEL condition that is written against a representation of a supported service resource. This field can contain up to 1000 characters. For example, "resource.machineType.contains('/machineTypes/n2d')".

For more information about the resources available to write conditions against, see Supported resources.

• ACTION: the action to take if the condition is met. Possible values are ALLOW and DENY.

The allow action means that if the condition evaluates to true, the operation to create or update the resource is permitted. This also means that every other case except the one explicitly listed in the condition is blocked.

The deny action means that if the condition evaluates to true, the operation to create or update the resource is blocked.

• DISPLAY_NAME: a human-readable name for the constraint. This name is used in error messages and can be used for identification and debugging. Don't use PII or sensitive data in display names because this name could be exposed in error messages. This field can contain up to 200 characters.
• DESCRIPTION: a human-friendly description of the constraint to display as an error message when the policy is violated. This field can contain up to 2000 characters.
2. After you have created the YAML file for a new custom constraint, 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.

After this operation is complete, your custom constraints are available as organization policies in your list of Google Cloud organization policies.

3. 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 organization policy

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

Console

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

   Go to Organization policies

2. From the project picker, select the project that you want to set the organization policy for.
3. From the list on the Organization policies page, select your constraint to view the Policy details page for that constraint.
4. To configure the organization policy for this resource, click Manage policy.
5. On the Edit policy page, select Override parent's policy.
6. Click Add a rule.
7. In the Enforcement section, select whether this organization policy is enforced or not.
8. Optional: 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 information, see Scope organization policies with tags.
9. Click Test changes to simulate the effect of the organization policy. For more information, see Test organization policy changes with Policy Simulator.
10. To enforce the organization policy in dry-run mode, click Set dry run policy. For more information, see Test organization policies.
11. After you verify that the organization policy in dry-run mode works as intended, set the live policy by clicking Set policy.

gcloud

1. To create an organization policy with boolean rules, create a policy YAML file that references the constraint:

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

dryRunSpec:
  rules:
  - enforce: true

Replace the following:

• PROJECT_ID: the project that you want to enforce your constraint on.
• CONSTRAINT_NAME: the name you defined for your custom constraint. For example, custom.createOnlyN2DVMs.
2. To enforce the organization policy in dry-run mode, run the following command with the dryRunSpec flag:

gcloud org-policies set-policy POLICY_PATH --update-mask=dryRunSpec

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

3. After you verify that the organization policy in dry-run mode works as intended, set the live policy with the org-policies set-policy command and the spec flag:

gcloud org-policies set-policy POLICY_PATH --update-mask=spec

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

Test the custom organization policy

The following example creates a custom constraint that restricts VMs to use the N2D machine type.

Create the custom constraint

1. To define a custom constraint, create a file named onlyN2DVMs.yaml.

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

   Replace ORGANIZATION_ID with your organization ID.

2. Apply the custom constraint.

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

Create the organization policy

1. To define an organization policy, create a file named onlyN2DVMs-policy.yaml. In this example we enforce this constraint at the project level but you might also set this at the organization or folder level.

   name: projects/PROJECT_ID/policies/custom.createOnlyN2DVMs
   spec:
     rules:
     – enforce: true

   Replace PROJECT_ID with your project ID.

2. Enforce the organization policy.

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

Test the policy

1. 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 operation is disallowed and 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 organization policies for common use cases

This table provides syntax examples for some common custom constraints.

Description	Constraint syntax
Persistent Disk type must be "Extreme persistent disk (pd-extreme)"	name: organizations/ORGANIZATION_ID/customConstraints/custom.createDisksPDExtremeOnly resourceTypes: compute.googleapis.com/Disk condition: "resource.type.contains('pd-extreme')" actionType: ALLOW methodTypes: CREATE displayName: 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 resourceTypes: compute.googleapis.com/Disk condition: "resource.sizeGb <= 250" actionType: ALLOW methodTypes: CREATE displayName: Disks size maximum is 250 GB description: Restrict the boot disk size to 250 GB or less for all VMs.
Source images must be from Cloud Storage test_bucket only	name: organizations/ORGANIZATION_ID/customConstraints/custom.createDisksfromStoragebucket resourceTypes: compute.googleapis.com/Image condition: "resource.rawDisk.source.contains('storage.googleapis.com/test_bucket/')" actionType: ALLOW methodTypes: CREATE displayName: 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 must have a label with the key set to cost center	name: organizations/ORGANIZATION_ID/customConstraints/custom.createVMWithLabel resourceTypes: compute.googleapis.com/Instance condition: "'cost_center' in resource.labels" actionType: ALLOW methodTypes: CREATE displayName: 'cost_center' label required description: Requires that all VMs created must have 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 resourceTypes: compute.googleapis.com/Instance condition: "'cost_center' in resource.labels and resource.labels['cost_center'] == 'eCommerce'" actionType: ALLOW methodTypes: CREATE displayName: 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 resourceTypes: compute.googleapis.com/Instance condition: "resource.machineType.contains('/machineTypes/n2d')" actionType: ALLOW methodTypes: CREATE displayName: 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 resourceTypes: compute.googleapis.com/Instance condition: "resource.machineType.endsWith('-e2-highmem-8')" actionType: ALLOW methodTypes: CREATE displayName: 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 resourceTypes: compute.googleapis.com/Instance condition: "resource.scheduling.nodeAffinities.exists(n, n.key == 'foo')" actionType: ALLOW methodTypes: CREATE displayName: Only VMs scheduled on node group "foo" allowed description: Restrict all VMs created to use the node group "foo".

Compute Engine supported resources

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

Resource	Field
compute.googleapis.com/Disk	resource.enableConfidentialCompute
	resource.licenseCodes
	resource.licenses
	resource.sizeGb
	resource.sourceImage
	resource.type
compute.googleapis.com/Image	resource.rawDisk.source
compute.googleapis.com/Instance	resource.advancedMachineFeatures.enableNestedVirtualization
	resource.advancedMachineFeatures.performanceMonitoringUnit
	resource.advancedMachineFeatures.threadsPerCore
	resource.canIpForward
	resource.confidentialInstanceConfig.confidentialInstanceType
	resource.confidentialInstanceConfig.enableConfidentialCompute
	resource.deletionProtection
	resource.guestAccelerators.acceleratorCount
	resource.guestAccelerators.acceleratorType
	resource.labels
	resource.machineType
	resource.minCpuPlatform
	resource.name
	resource.networkInterfaces.accessConfigs.name
	resource.networkInterfaces.accessConfigs.natIP
	resource.networkInterfaces.network
	resource.networkInterfaces.networkAttachment
	resource.networkInterfaces.subnetwork
	resource.privateIpv6GoogleAccess
	resource.resourceStatus.effectiveInstanceMetadata.blockProjectSshKeysMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.enableGuestAttributesMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.enableOsconfigMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.enableOsInventoryMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.enableOsloginMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.serialPortEnableMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.serialPortLoggingEnableMetadataValue
	resource.resourceStatus.effectiveInstanceMetadata.vmDnsSettingMetadataValue
	resource.scheduling.nodeAffinities.key
	resource.scheduling.nodeAffinities.operator
	resource.scheduling.nodeAffinities.values
	resource.selfLink
	resource.shieldedInstanceConfig.enableIntegrityMonitoring
	resource.shieldedInstanceConfig.enableSecureBoot
	resource.shieldedInstanceConfig.enableVtpm
	resource.zone
compute.googleapis.com/InstanceGroup	resource.description
	resource.name
	resource.namedPorts.name
	resource.namedPorts.port

Enforcing Mandatory Resource Manager Tags

Some Compute Engine resources also support the GOVERN_TAGS type constraint to enforce mandatory Resource Manager tags on the Compute Engine resource. For more information, see Enforcement of mandatory tags using organization policies.

Pricing

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

What's next

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