Create custom organization policy constraints for Cloud KMS

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

  • cloudkms.googleapis.com/KeyHandle
  • cloudkms.googleapis.com/AutokeyConfig
  • cloudkms.googleapis.com/CryptoKey
  • cloudkms.googleapis.com/CryptoKeyVersion
  • cloudkms.googleapis.com/EkmConnection
  • cloudkms.googleapis.com/EkmConfig
  • cloudkms.googleapis.com/ImportJob

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 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 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.

Before you begin

  1. 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.

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

    Go to project selector

  3. Make sure that billing is enabled for your Google Cloud project.

  4. Install the Google Cloud CLI.

  5. To initialize the gcloud CLI, run the following command: 

    gcloud init
    6.

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

    Go to project selector

  7. Make sure that billing is enabled for your Google Cloud project.

  8. Install the Google Cloud CLI.

  9. To initialize the gcloud CLI, run the following command: 

    gcloud init
    10.
  10. Ensure that you know your organization ID.

Required roles

To get the permissions that you need to manage custom organization policies, ask your administrator to grant you the Organization Policy Administrator (roles/orgpolicy.policyAdmin) IAM role on the organization resource. For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.

Create 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.

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 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.maxKeyRotationPeriod. The maximum length of this field is 70 characters.

  • RESOURCE_NAME: the fully qualified name of the Google Cloud resource containing the object and field you want to restrict. For example, cloudkms.googleapis.com/CryptoKey.

  • 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.rotationPeriod <= duration('90d')".

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

Set up a custom constraint

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. Once completed, your custom constraints are available as 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 organization policy

You can enforce a boolean 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 for which you want to set the organization policy.
  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 enforcement of this organization policy is on or off.
  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 Setting an organization policy with tags.
  9. 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.
  10. To finish and apply the organization policy, click Set policy. The policy requires 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.maxKeyRotationPeriod.

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 requires up to 15 minutes to take effect.

Example custom organization policies for common use cases

The following table provides the syntax of some custom constraints for common use cases:

Description Constraint syntax
Set a maximum rotation period of 90 days 
    name: organizations/ORGANIZATION_ID/customConstraints/custom.maxRotationPeriod
    resourceTypes:
    - cloudkms.googleapis.com/CryptoKey
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.rotationPeriod <= duration('90d')"
    actionType: ALLOW
    displayName: Enforce maximum rotation period for Cloud KMS keys
    description: The maximum rotation period for Cloud KMS keys is 90 days.
Set a maximum scheduled for destruction duration of 180 days 
    name: organizations/ORGANIZATION_ID/customConstraints/custom.maxRotationPeriod
    resourceTypes:
    - cloudkms.googleapis.com/CryptoKey
    methodTypes:
    - CREATE
    condition: "resource.destroyScheduledDuration <= duration('180d')"
    actionType: ALLOW
    displayName: Enforce maximum scheduled for destruction duration
    description: The maximum length of the scheduled for destruction period is 180 days.
Require the HSM protection level for imported keys 
    name: organizations/ORGANIZATION_ID/customConstraints/custom.importToHSM
    resourceTypes:
    - cloudkms.googleapis.com/ImportJob
    methodTypes:
    - CREATE
    condition: "resource.protectionLevel == 'HSM'"
    actionType: ALLOW
    displayName: Import to HSM keys only
    description: New ImportJob resources must use the HSM protection level.

Cloud Key Management Service supported resources

The following table lists the Cloud Key Management Service resources that you can reference in custom constraints.

Resource Field
cloudkms.googleapis.com/AutokeyConfig resource.keyProject
resource.name
cloudkms.googleapis.com/CryptoKey resource.cryptoKeyBackend
resource.destroyScheduledDuration
resource.importOnly
resource.keyAccessJustificationsPolicy.allowedAccessReasons
resource.nextRotationTime
resource.purpose
resource.rotationPeriod
resource.versionTemplate.algorithm
resource.versionTemplate.protectionLevel
cloudkms.googleapis.com/CryptoKeyVersion resource.externalProtectionLevelOptions.ekmConnectionKeyPath
resource.externalProtectionLevelOptions.externalKeyUri
resource.state
cloudkms.googleapis.com/EkmConfig resource.defaultEkmConnection
cloudkms.googleapis.com/EkmConnection resource.cryptoSpacePath
resource.keyManagementMode
resource.serviceResolvers.endpointFilter
resource.serviceResolvers.hostname
resource.serviceResolvers.serviceDirectoryService
cloudkms.googleapis.com/ImportJob resource.importMethod
resource.protectionLevel
cloudkms.googleapis.com/KeyHandle resource.name
resource.resourceTypeSelector

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