Manage resources by using custom constraints

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

  • networkservices.googleapis.com/LbRouteExtension
  • networkservices.googleapis.com/LbTrafficExtension

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.

Benefits

You can use custom organization policies with Service Extensions to do the following:

  • Allow only one type of the load balancing scheme
  • Disallow certain supported events types
  • Restrict the number of extension chains and extensions

Before you begin

  • Ensure that you know your organization ID.
  • Install and initialize the Google Cloud CLI.
    1. Install the Google Cloud CLI.

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

      gcloud init

    • 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.LbTrafficExtensionDenyBodyEvents. 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, networkservices.googleapis.com/LbTrafficExtension.

    • 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.extensionChains.all(value, value.extensions.all(value, value.supportedEvents.all(value, value.contains("BODY"))))".

    • 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.LbTrafficExtensionDenyBodyEvents.

    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.

    Test the custom organization policy

    The following example creates a custom constraint that prevents Cloud Load Balancing traffic extensions from modifying the request body or the response body.

    Create the constraint

    1. To define the constraint, create a file named constraint-deny-body-events.yaml with the following contents:

      name: organizations/ORGANIZATION_ID/customConstraints/custom.LbTrafficExtensionDenyBodyEvents
resourceTypes:
- networkservices.googleapis.com/LbTrafficExtension
methodTypes:
- CREATE
- UPDATE
condition: resource.extensionChains.all(value, value.extensions.all(value, value.supportedEvents.all(value, value.contains("BODY"))))
actionType: DENY
displayName: Deny body modifications by traffic extensions.
description: Deny traffic extensions that are called for REQUEST_BODY or RESPONSE_BODY.

      Replace ORGANIZATION_ID with your organization ID.

    2. Apply the constraint:

      gcloud org-policies set-custom-constraint ~/constraint-deny-body-events.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.LbTrafficExtensionDenyBodyEvents  DENY         CREATE,UPDATE    networkservices.googleapis.com/LbTrafficExtension   Deny body modifications by traffic extensions.
...

    Create the policy

    1. Create a file named policy-deny-body-events.yaml file with the following policy:

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

      Replace PROJECT_ID with your project ID.

    2. Apply the policy:

      gcloud org-policies set-policy ~/policy-deny-body-events.yaml

    3. Verify that the policy exists:

      gcloud org-policies list --project=PROJECT_ID

      The output is similar to the following:

      CONSTRAINT                               LIST_POLICY    BOOLEAN_POLICY    ETAG
custom.LbTrafficExtensionDenyBodyEvents  -              SET               COCsm5QGENiXi2E=

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

    Test the policy

    Test the policy by creating a Cloud Load Balancing traffic extension with the supportedEvents field set to REQUEST_BODY:

    gcloud service-extensions lb-traffic-extensions import TRAFFIC_EXTENSION_NAME \
    --source=PATH_TO_EXTENSION_FILE \
    --location=LOCATION_ID

    Replace the following:

    • TRAFFIC_EXTENSION_NAME: a unique name for the traffic extension
    • PATH_TO_EXTENSION_FILE: the path of the extension file
    • LOCATION_ID: the location of the project

    The output is similar to the following:

    ERROR: (gcloud.service-extensions.lb-traffic-extensions.import)
FAILED_PRECONDITION: Operation denied by custom org policy on resource
'projects/123456/locations/global/lbTrafficExtensions/trafficExtension1':
["customConstraints/custom.prohibitBodyModifyingEvents":
"Deny traffic extensions that are called for REQUEST_BODY or RESPONSE_BODY."].

    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
    Require all Cloud Load Balancing route extensions to have the INTERNAL_MANAGED load balancing scheme 
        name: organizations/ORGANIZATION_ID/customConstraints/custom.lbRouteExtensionInternalManaged
    resourceTypes:
    - networkservices.googleapis.com/LbRouteExtension
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.loadBalancingScheme == INTERNAL_MANAGED"
    actionType: ALLOW
    displayName: Require all Cloud Load Balancing route extensions to
    have the INTERNAL_MANAGED load balancing scheme
    description: All Cloud Load Balancing route extensions must have the
    INTERNAL_MANAGED load balancing scheme.

    Service Extensions supported resources

    The following table lists the Service Extensions resources that you can reference in custom constraints.

    Resource Field
    networkservices.googleapis.com/LbRouteExtension resource.description
    resource.extensionChains.extensions.authority
    resource.extensionChains.extensions.failOpen
    resource.extensionChains.extensions.forwardHeaders
    resource.extensionChains.extensions.name
    resource.extensionChains.extensions.timeout
    resource.extensionChains.name
    resource.loadBalancingScheme
    resource.name
    networkservices.googleapis.com/LbTrafficExtension resource.description
    resource.extensionChains.extensions.authority
    resource.extensionChains.extensions.failOpen
    resource.extensionChains.extensions.forwardHeaders
    resource.extensionChains.extensions.name
    resource.extensionChains.extensions.supportedEvents
    resource.extensionChains.extensions.timeout
    resource.extensionChains.name
    resource.loadBalancingScheme
    resource.name

    What's next