Manage Cloud Storage resources 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:

• storage.googleapis.com/Bucket

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.

Limitations

• Bucket labels aren't recommended for use in custom constraint conditions. Instead, use tags, which can only be set by individuals with required Identity and Access Management (IAM) roles and are more tightly controlled than labels.

• Newly enforced custom constraints don't apply to existing resources. Existing resources must be updated for the constraint to apply.

  To find existing resources that will need to be updated, you can enforce a dry-run organization policy.

• Custom constraints can't be used to constrain ACLs or IAM policies on objects or buckets.

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 (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

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 (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

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, ask your administrator to grant you the following IAM roles:

• Organization Policy Administrator (roles/orgpolicy.policyAdmin) on the organization
• Test the example organization policy on this page by creating a bucket: Storage Admin (roles/storage.admin) 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. To see the exact permissions that are required, expand the Required permissions section:

You might also be able to get these permissions with 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.bucketNamingRequirement. 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, storage.googleapis.com/Bucket.

• 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.name.matches('^[a-zA-Z]+$')".

• 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

gcloud org-policies set-custom-constraint CONSTRAINT_PATH

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

Enforce a custom organization policy

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

    gcloud org-policies set-policy POLICY_PATH
    

Test the custom organization policy

The following example creates a custom constraint and policy that require all newly created buckets to have a name that contains only letters. You can test the policy by trying to take an action that the policy should prevent.

Create the constraint

1. Save the following file as constraint-bucket-names.yaml:

   name: organizations/ORGANIZATION_ID/customConstraints/custom.bucketNamingRequirement
   resource_types: storage.googleapis.com/Bucket
   method_types:
   - CREATE
   condition: "resource.name.matches('^[a-zA-Z]+$')"
   action_type: ALLOW
   display_name: Bucket names must match the specified regular expression
   description: Newly created buckets must have a name that matches the specified regular expression. Only letters are allowed in the bucket name.
   

   Replace ORGANIZATION_ID with your organization ID.

2. Apply the constraint:

   gcloud org-policies set-custom-constraint ~/constraint-bucket-names.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.bucketNamingRequirement    ALLOW          CREATE          storage.googleapis.com/Bucket   Bucket names must match the specified regular expression
   ...
   

Create the policy

1. Save the following file as policy-bucket-names.yaml:

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

   Replace PROJECT_ID with your project ID.

   In this example, you enforce this constraint at the project level, but you might also set this at the organization or folder level.

2. Apply the policy:

   gcloud org-policies set-policy ~/policy-bucket-names.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.bucketNamingRequirement    -              SET               CIqktscGELiZn6cC-
   

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

Test the policy

• Try to create a bucket with a name that contains a character that isn't a letter:

  gcloud storage buckets create gs://example-bucket --location=BUCKET_LOCATION
  

  Replace BUCKET_LOCATION with the location of the bucket. For example, US.

  The request fails with an error similar to the following:

  ERROR: (gcloud.storage.buckets.create) HTTPError 412: orgpolicy:projects/_/buckets/example-bucket violates customConstraints/custom.bucketNamingRequirement. Details: Newly created buckets must have a name that matches the specified regular expression. Only letters are allowed in the bucket name.
  

Example custom organization policies for common use cases

The following table provides syntax examples for some common custom constraints. For a list of predefined constraints that you can use with Cloud Storage, see Organization policy constraints for Cloud Storage.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.enforceBucketVersioning
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "resource.versioning.enabled == true"
  action_type: ALLOW
  display_name: Buckets must have Object Versioning enabled
  description: Newly created buckets and newly updated buckets must have Object Versioning enabled.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.bucketNamingRequirement
  method_types:
  - CREATE
  resource_types: storage.googleapis.com/Bucket
  condition: "resource.name.matches('^[a-zA-Z]+$')"
  action_type: ALLOW
  display_name: Bucket names must match the specified regular expression
  description: Newly created buckets must have a name that matches the specified regular expression. Only letters are allowed in the bucket name.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.prohibitBucketLock
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "resource.retentionPolicy.isLocked == true"
  action_type: DENY
  display_name: Prohibit the use of Bucket Lock
  description: Newly created buckets and newly updated buckets cannot have Bucket Lock enabled.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.prohibitObjectRetentionLock
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "resource.objectRetention.mode == 'Enabled'"
  action_type: DENY
  display_name: Objects cannot have retention configurations
  description: Newly created buckets and newly updated buckets cannot have Object Retention Lock enabled.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.locationRetentionPolicy
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "(resource.location.startsWith('US') || resource.location.startsWith('EU')) && resource.retentionPolicy.retentionPeriod != 86400"
  action_type: DENY
  display_name: All buckets in US and EU must have a retention policy of 86,400 seconds
  description: Newly created buckets and newly updated buckets located in US and EU regions must have a retention policy of 86,400 seconds.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.labels
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "'my_annotations.data.source' in resource.labels && resource.labels['my_annotations.data.source'] in ['SOURCE_IMAGES','SOURCE_TEXT','SOURCE_VIDEOS']"
  action_type: ALLOW
  display_name: Buckets must have a label classifying the contents of the bucket
  description: Newly created buckets and newly updated buckets must have the label my_annotations.data.source with the SOURCE_IMAGES, SOURCE_TEXT, or SOURCE_VIDEOS key.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.dualRegionUS
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "'US-EAST1' in resource.customPlacementConfig.dataLocations && 'US-EAST4' in resource.customPlacementConfig.dataLocations"
  action_type: ALLOW
  display_name: Buckets must be located in a dual-region
  description: Newly created buckets and newly updated buckets must be located in a dual-region composed of the us-east1 and us-east4 regions.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.disableLegacyStorageClass
  method_types:
  - CREATE
  - UPDATE
  resource_types: storage.googleapis.com/Bucket
  condition: "resource.storageClass in ['STANDARD', 'NEARLINE', 'COLDLINE', 'ARCHIVE']"
  action_type: ALLOW
  display_name: Buckets cannot use legacy storage classes
  description: Newly created buckets and newly updated buckets must use Standard storage, Nearline storage, Coldline storage, or Archive storage.

  name: organizations/ORGANIZATION_ID/customConstraints/custom.IpFilter
  method_types:
  - CREATE
  resource_types: storage.googleapis.com/Bucket
  condition: "!has(resource.ipFilter) || (resource.ipFilter.mode == 'Disabled' || resource.ipFilter.publicNetworkSource.allowedIpCidrRanges.size() > 0)"
  action_type: DENY
  display_name: Bucket IP filter rules must restrict all the public network
  description: Newly created buckets must have IP filtering and IP filtering rules must restrict all public network resources. 

Conditional organization policies

You can make a custom organization policy conditional by using tags. For more information, see Setting an organization policy with tags.

Cloud Storage supported resources

The following table lists the Cloud Storage resources that you can reference in custom constraints.

Note the following:

• You must use uppercase to specify the values for the following fields:
  • resource.customPlacementConfig.dataLocations
  • resource.lifecycle.rule.action.storageClass
  • resource.location
  • resource.storageClass
• The resource.retentionPolicy.isLocked field can only be used to prohibit the use of Bucket Lock, not to enforce Bucket Lock.

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.