Manage Memorystore for Redis resources with 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 organization policies.

By implementing a custom organization policy you enforce consistent configurations and restrictions. This ensures that your Memorystore for Redis instances adhere to security best practices and regulatory requirements.

Benefits

You can use a custom organization policy to allow or deny specific Memorystore for Redis resources. For example, if a request to create or update a Redis instance fails to satisfy custom constraint validation as set by your organization policy, the request will fail and an error will be returned to the caller.

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

Like all organization policy constraints, policy changes don't apply retroactively to existing instances.

  • A new policy doesn't impact existing instance configurations.
  • An existing instance configuration remains valid, unless you change the instance configuration from a compliance to non-compliance state using the Google Cloud console, Google Cloud CLI, or RPC.
  • A scheduled maintenance update doesn't cause a policy enforcement, because maintenance doesn't change the configuration of instances.

Before you begin

  1. Set up your project.
    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. 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. Ensure that you know your organization ID.

Required roles

To get the permissions that you need to manage 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.

You also need to add required roles to create Memorystore for Redis to your user account. See Configuring access to Memorystore for Redis resources.

Create a custom constraint

You can create a custom constraint by using a YAML file to define the resources, methods, conditions, and actions that are subject to the constraint. These are specific to the service on which you're enforcing the organization policy. Conditions for your custom constraints must be defined using Common Expression Language. See the GitHub page about 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.

Use the following template to create a YAML file for a custom constraint:

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resourceTypes:
- redis.googleapis.com/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.restrictInstanceToOnereplica. The maximum length of this field is 70 characters, not counting the prefix, for example, organizations/123456789/customConstraints/custom.allowConstraint.

  • RESOURCE_NAME: the name (not the URI) of the Memorystore for Redis 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.replicaCount >= 2".

  • 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.

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, 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 organization policy

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:

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

    Go to Organization policies

  2. Select the project picker at the top of the page.
  3. From the project picker, select the project for which you want to set the organization policy.
  4. Select your constraint from the list on the Organization policies page. The Policy details page for that constraint should appear.
  5. To configure the organization policy for this resource, click Manage policy.
  6. On the Edit policy page, select Override parent's policy.
  7. Click Add a rule.
  8. Under Enforcement, select whether enforcement of this organization policy should be on or off.
  9. 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.
  10. 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.
  11. 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.restrictInstanceToOnereplica.

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.

Test a custom constraint

To test a custom constraint, run a gcloud command that attempts to create a Redis instance.

For example, assume that a constraint requires that Redis instances should not have more than one replica. You could test this constraint by running the gcloud redis instances create command with replica-count set to 2 as demonstrated in the following snippet:

gcloud redis instances create redis-test-instance \
    --project=my-project \
    --tier=standard \
    --size=16 \
    --region=us-central1 \
    --redis-version=redis_7_0 \
    --network=projects/my-project/global/networks/default \
    --connect-mode=PRIVATE_SERVICE_ACCESS \
    --read-replicas-mode=READ_REPLICAS_ENABLED \
    --replica-count=2

The output is similar to the following:

Operation denied by custom org policies: ["customConstraints/custom.restrictInstanceToOnereplica": "Prevent users from creating Redis instances with more than one replica"]

Memorystore for Redis supported resources and operations

The following Memorystore for Redis custom constraint fields are available to use when you create or update a Memorystore for Redis resource.

  • Memorystore for Redis Instance
    • resource.alternativeLocationId
    • resource.authEnabled
    • resource.authorizedNetwork
    • resource.availableMaintenanceVersions
    • resource.connectMode
    • resource.customerManagedKey
    • resource.displayName
    • resource.locationId
    • resource.maintenancePolicy.description
    • resource.maintenancePolicy.weeklyMaintenanceWindow.day
    • resource.maintenanceVersion
    • resource.memorySizeGb
    • resource.name
    • resource.persistenceConfig.persistenceMode
    • resource.persistenceConfig.rdbSnapshotPeriod
    • resource.persistenceConfig.rdbSnapshotStartTime
    • resource.readReplicasMode
    • resource.redisConfigs
    • resource.redisVersion
    • resource.replicaCount
    • resource.reservedIpRange
    • resource.secondaryIpRange
    • resource.suspensionReasons
    • resource.tier
    • resource.transitEncryptionMode

Example custom constraints

The following table provides an example custom constraint that restricts Redis instance to one replica:

Description Constraint syntax
Restrict Redis instances with one replicas 

    name: organizations/ORGANIZATION_ID/customConstraints/custom.restrictInstanceToOnereplica
    resourceTypes:
    - redis.googleapis.com/Instance
    methodTypes:
    - CREATE
    - UPDATE
    condition: "resource.replicaCount >= 2"
    actionType: DENY
    displayName: Restrict Redis instances to one replica
    description: Prevent users from creating Redis instances with more than one replica

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