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

  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.

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

    Go to project selector

  3. Verify 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.

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

    Go to project selector

  8. Verify 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 organization policies, ask your administrator to grant you the following IAM roles:

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:

Required permissions

The following permissions are required to manage organization policies:

  • orgpolicy.* on the organization
  • Test the example organization policy on this page by creating a bucket: storage.buckets.create on the project

You might also be able to get these permissions with custom roles or other predefined roles.

Set up 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.

Console

To create a custom constraint, do the following:

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

    Go to Organization policies

  2. From the project picker, select the project that you want to set the organization policy for.
  3. Click Custom constraint.
  4. In the Display name box, enter a human-readable name for the constraint. This name is used in error messages and can be used for identification and debugging. Don't use PII or sensitive data in display names because this name could be exposed in error messages. This field can contain up to 200 characters.
  5. In the Constraint ID box, enter the name that you want for your new custom constraint. A custom constraint can only contain letters (including upper and lowercase) or numbers, for example custom.disableGkeAutoUpgrade. This field can contain up to 70 characters, not counting the prefix (custom.), for example, organizations/123456789/customConstraints/custom. Don't include PII or sensitive data in your constraint ID, because it could be exposed in error messages.
  6. In the Description box, enter a human-readable description of the constraint. This description is used as an error message when the policy is violated. Include details about why the policy violation occurred and how to resolve the policy violation. Don't include PII or sensitive data in your description, because it could be exposed in error messages. This field can contain up to 2000 characters.
  7. In the Resource type box, select the name of the Google Cloud REST resource containing the object and field that you want to restrict—for example, container.googleapis.com/NodePool. Most resource types support up to 20 custom constraints. If you attempt to create more custom constraints, the operation fails.
  8. Under Enforcement method, select whether to enforce the constraint on a REST CREATE method or on both CREATE and UPDATE methods. If you enforce the constraint with the UPDATE method on a resource that violates the constraint, changes to that resource are blocked by the organization policy unless the change resolves the violation.

    9. Not all Google Cloud services support both methods. To see supported methods for each service, find the service in Supported services.

  9. To define a condition, click Edit condition.
    1. In the Add condition panel, create a CEL condition that refers to a supported service resource, for example, resource.management.autoUpgrade == false. This field can contain up to 1000 characters. For details about CEL usage, see Common Expression Language. For more information about the service resources you can use in your custom constraints, see Custom constraint supported services.
    2. Click Save.
  10. Under Action, select whether to allow or deny the evaluated method if the condition is met.

    11. The deny action means that the operation to create or update the resource is blocked if the condition evaluates to true.

    The allow action means that the operation to create or update the resource is permitted only if the condition evaluates to true. Every other case except ones explicitly listed in the condition is blocked.

  11. Click Create constraint.

    12. When you have entered a value into each field, the equivalent YAML configuration for this custom constraint appears on the right.

gcloud

  1. To create a custom constraint, create a YAML file using the following format: 
    2.       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 that you want for your new custom constraint. A custom constraint can only contain letters (including upper and lowercase) or numbers, for example, custom.bucketNamingRequirement. This field can contain up to 70 characters.
    • RESOURCE_NAME: the fully qualified name of the Google Cloud resource containing the object and field that 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 can contain up to 1000 characters. For example, "resource.name.matches('^[a-zA-Z]+$')".

      • For more information about the resources available to write conditions against, see Supported resources.

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

      • The allow action means that if the condition evaluates to true, the operation to create or update the resource is permitted. This also means that every other case except the one explicitly listed in the condition is blocked.

      The deny action means that if the condition evaluates to true, the operation to create or update the resource is blocked.

    • DISPLAY_NAME: a human-friendly name for the constraint. This field can contain up to 200 characters.
    • DESCRIPTION: a human-friendly description of the constraint to display as an error message when the policy is violated. This field can contain up to 2000 characters.
  2. 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: 
    3.         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.

    After this operation is complete, your custom constraints are available as organization policies in your list of Google Cloud organization policies.

  3. To verify that the custom constraint exists, use the gcloud org-policies list-custom-constraints command: 
    4.       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 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 that you want to set the organization policy for.
  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 this organization policy is enforced or not.
  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. Click Test changes to simulate the effect of the organization policy. For more information, see Test organization policy changes with Policy Simulator.
  10. To enforce the organization policy in dry-run mode, click Set dry run policy. For more information, see Create an organization policy in dry-run mode.
  11. After you verify that the organization policy in dry-run mode works as intended, set the live policy by clicking Set policy.

gcloud

  1. To create an organization policy with boolean rules, create a policy YAML file that references the constraint: 
    2.         name: projects/PROJECT_ID/policies/CONSTRAINT_NAME
        spec:
          rules:
          - enforce: true
        
        dryRunSpec:
          rules:
          - enforce: true

    Replace the following:

    • PROJECT_ID: the project that you want to enforce your constraint on.
    • CONSTRAINT_NAME: the name you defined for your custom constraint. For example, custom.bucketNamingRequirement.
  2. To enforce the organization policy in dry-run mode, run the following command with the dryRunSpec flag: 
    3.         gcloud org-policies set-policy POLICY_PATH \
          --update-mask=dryRunSpec

    Replace POLICY_PATH with the full path to your organization policy YAML file. The policy requires up to 15 minutes to take effect.

  3. After you verify that the organization policy in dry-run mode works as intended, set the live policy with the org-policies set-policy command and the spec flag: 
    4.         gcloud org-policies set-policy POLICY_PATH \
          --update-mask=spec

    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 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.

Description Constraint syntax
Buckets must have Object Versioning enabled 
  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.
Buckets must be named using a specific regular expression 
  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.
Buckets cannot have Bucket Lock enabled 
  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.
Buckets cannot have Object Retention 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.
Buckets located in the US or EU multi-regions must have a retention period of 86,400 seconds 
  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.
Buckets must have labels1 
  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.
Buckets must be located in a dual-region 
  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.
Buckets cannot use legacy storage classes 
  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.
Bucket IP filtering must restrict requests from all the public internet 
  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.

1 Specifying a bucket label key that does not exist returns a BAD_CONDITION error. This error blocks the CREATE and UPDATE methods from being run on the bucket. To avoid this error, always check that the label key exists first by using "my_annotations.data.source" in resource.labels.

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.

Resource Field
storage.googleapis.com/Bucket resource.billing.requesterPays
resource.cors.maxAgeSeconds
resource.cors.method
resource.cors.origin
resource.cors.responseHeader
resource.customPlacementConfig.dataLocations
resource.defaultEventBasedHold
resource.encryption.defaultKmsKeyName
resource.iamConfiguration.publicAccessPrevention
resource.iamConfiguration.uniformBucketLevelAccess.enabled
resource.ipFilter.mode
resource.ipFilter.publicNetworkSource.allowedIpCidrRanges
resource.ipFilter.vpcNetworkSources.allowedIpCidrRanges
resource.ipFilter.vpcNetworkSources.network
resource.labels
resource.lifecycle.rule.action.storageClass
resource.lifecycle.rule.action.type
resource.lifecycle.rule.condition.age
resource.lifecycle.rule.condition.createdBefore
resource.lifecycle.rule.condition.customTimeBefore
resource.lifecycle.rule.condition.daysSinceCustomTime
resource.lifecycle.rule.condition.daysSinceNoncurrentTime
resource.lifecycle.rule.condition.isLive
resource.lifecycle.rule.condition.matchesPrefix
resource.lifecycle.rule.condition.matchesStorageClass
resource.lifecycle.rule.condition.matchesSuffix
resource.lifecycle.rule.condition.noncurrentTimeBefore
resource.lifecycle.rule.condition.numNewerVersions
resource.location
resource.locationType
resource.logging.logBucket
resource.logging.logObjectPrefix
resource.name
resource.objectRetention.mode
resource.retentionPolicy.isLocked
resource.retentionPolicy.retentionPeriod
resource.rpo
resource.softDeletePolicy.retentionDurationSeconds
resource.storageClass
resource.versioning.enabled
resource.website.mainPageSuffix
resource.website.notFoundPage

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