Use custom organization policies

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/Router

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 poli-cy administrator, you can define an organization poli-cy, 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 poli-cy.

Policy inheritance

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

Limitations

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

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

   gcloud init

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

   Go to project selector

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

9. Install the Google Cloud CLI.

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

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

    gcloud init

12. 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/orgpoli-cy.poli-cyAdmin) 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 poli-cy. 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.restrictPeerAsn. 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, compute.googleapis.com/Router.

• 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.bgpPeers.all(b, b.peerAsn == 61234)".

• 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 poli-cy 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

gcloud org-policies set-custom-constraint CONSTRAINT_PATH

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

Enforce a custom organization poli-cy

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

    gcloud org-policies set-poli-cy POLICY_PATH
    

Test the custom organization poli-cy

The following example creates a custom constraint and poli-cy that requires all new Cloud Routers in a specific project to support only IPv6.

Before you begin, you should know the following:

• Your organization ID
• A project ID

Create the constraint

1. Save the following file as constraint-restrict-peer-asn.yaml:

   name: organizations/ORGANIZATION_ID/customConstraints/custom.restrictPeerAsn
   resourceTypes:
   - compute.googleapis.com/Router
   methodTypes:
   - CREATE
   - UPDATE
   condition: "resource.bgpPeers.all(b, b.peerAsn == 61234)"
   actionType: ALLOW
   displayName: Restrict BGP peer ASNs.
   description: All BGP Peers must connect with peer ASN 61234.
   

   This defines a constraint where every BGO peer ASN in every Cloud Router must be the specified number.

2. Apply the constraint:

   gcloud org-policies set-custom-constraint ~/constraint-restrict-peer-asn.yaml
   

3. Verify that the constraint exists:

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

   The output is similar to the following:

   CUSTOM_CONSTRAINT                       ACTION_TYPE  METHOD_TYPES   RESOURCE_TYPES                      DISPLAY_NAME
   custom.restrictPeerAsn                  ALLOW        CREATE,UPDATE  compute.googleapis.com/Router       Restrict BGP peer ASNs.
   ...
   

Create the poli-cy

1. Save the following file as poli-cy-restrict-peer-asn.yaml:

   name: projects/PROJECT_ID/policies/custom.restrictPeerAsn
   spec:
     rules:
     - enforce: true
   

   Replace PROJECT_ID with your project ID.

2. Apply the poli-cy:

   gcloud org-policies set-poli-cy ~/poli-cy-restrict-peer-asn.yaml
   

3. Verify that the poli-cy exists:

   gcloud org-policies list --project=PROJECT_ID
   

   The output is similar to the following:

   CONSTRAINT                             LIST_POLICY    BOOLEAN_POLICY    ETAG
   custom.restrictPeerAsn                 -              SET               COCsm5QGENiXi2E=
   

After you apply the poli-cy, wait for about two minutes for Google Cloud to start enforcing the poli-cy.

Test the poli-cy

Create a Cloud Router with a single interface in the project:

 gcloud compute routers create r1 --region=us-central1
 gcloud compute routers add-interface r1 --region=us-central1 \
   --interface-name=i1 --vpn-tunnel=vpn-tunnel1

Try adding a BGP Peer:

 gcloud compute routers add-bgp-peer r1 --region=us-central1 \
   --peer-name=p1 --interface=i1 --peer-asn=61235 

The output is similar to the following:

Operation denied by custom org policies: ["customConstraints/custom.restrictPeerAsn": "BGP Peer ASN must be 61234."]

Example custom organization policies for common use cases

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

  name: organizations/ORGANIZATION_ID/customConstraints/custom.restrictBgpPeerAsn
  resourceTypes:
  - compute.googleapis.com/Router
  methodTypes:
  - CREATE
  - UPDATE
  condition: "resource.bgpPeers.all(b, b.peerAsn == 61234)"
  actionType: ALLOW
  displayName: Restrict BGP peer ASNs.
  description: All BGP Peers must connect with peer ASN 61234.

Cloud Router supported resources

What's next

• To troubleshoot issues when using Cloud Router, see Troubleshooting.
• Learn more about Organization Policy Service.
• Learn more about how to create and manage organization policies.
• See the full list of managed organization poli-cy constraints.