Use custom organization policies for service accounts and service account keys

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.

Benefits

You can use custom organization policies to allow or deny specific operations on service accounts and service account keys. For example, you can set a policy to deny the creation of a key with a certain origin, causing any requests to create a key with that origin to fail and return an error to the user.

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.

Before you begin

Ensure that you know your organization ID.
If you want to test out custom organization policies that reference IAM resources, create a new project. Testing these organization policies in an existing project could disrupt security workflows.
1. In the Google Cloud console, go to the project selector page.
  
  Go to project selector
2. Select or create a Google Cloud project.
  
  Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

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. For more information about granting roles, see Manage access to projects, folders, and organizations.

This predefined role contains 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.constraints.list
orgpolicy.policies.create
orgpolicy.policies.delete
orgpolicy.policies.list
orgpolicy.policies.update
orgpolicy.policy.get
orgpolicy.policy.set

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 YAML file for a custom constraint:

name: organizations/ORGANIZATION_ID/customConstraints/CONSTRAINT_NAME
resourceTypes:
- iam.googleapis.com/RESOURCE_TYPE
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.denyServiceAccountCreation. The maximum length of this field is 70 characters, not counting the prefix, for example, organizations/123456789/customConstraints/custom.
RESOURCE_TYPE: the name (not the URI) of the Identity and Access Management API REST resource containing the object and field you want to restrict. For example, ServiceAccount.
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.description.contains('INVALID_DESCRIPTION')".
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 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

In the Google Cloud console, go to the Organization policies page.
Go to Organization policies
From the project picker, select the project for which you want to set the organization policy.
From the list on the Organization policies page, select your constraint to view the Policy details page for that constraint.
To configure the organization policy for this resource, click Manage policy.
On the Edit policy page, select Override parent's policy.
Click Add a rule.
In the Enforcement section, select whether enforcement of this organization policy is on or off.
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.
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.
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.denyServiceAccountCreation.

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

Optionally, you can test the organization policy by setting the policy and then trying to take an action that the policy should prevent.

This section describes how to test the following organization policy constraint:

name: organizations/ORG_ID/customConstraints/custom.denyServiceAccountCreation
resourceTypes: iam.googleapis.com/ServiceAccount
methodTypes:
  - CREATE
  - UPDATE
condition:
  "resource.description.contains('INVALID_DESCRIPTION')"
actionType: DENY
displayName: Do not allow service account with INVALID_DESCRIPTION to be created.

If you want to test this custom constraint, do the following:

Copy the constraint into a YAML file and replace the following values:
- ORG_ID: the numeric ID of your Google Cloud organization.
- INVALID_DESCRIPTION: the description that you want to use to test the custom constraint. While the constraint is active, service accounts with a description containing this string won't be created on the project that you enforce the constraint for.
Set up the custom constraint and enforce it for the project that you created to test the custom organization policy constraint.
Ensure that you have the Create Service Accounts role (roles/iam.serviceAccountCreator).
Try to create a service account with the description you included in the custom constraint. Before running the command, replace the following values:
- SERVICE_ACCOUNT_NAME: The name of the service account
- INVALID_DESCRIPTION: The invalid string that will be checked for in the description of the service account
- DISPLAY_NAME: The service account name to display in the Google Cloud console

gcloud iam service-accounts create SERVICE_ACCOUNT_NAME \
    --description="INVALID_DESCRIPTION" --display-name="DISPLAY_NAME"

The output is the following:

Operation denied by custom org policy: ["customConstraints/custom.denyServiceAccountCreation": "Do not allow service account with INVALID_DESCRIPTION to be created."]

Identity and Access Management supported resources and operations

The following service account and service account key custom constraint fields are available to use when you create or update an account or key.

Service accounts
- resource.description
- resource.displayName
- resource.name
  - Format: projects/PROJECT_ID/serviceAccounts/UNIQUE_ID
Service account keys
- resource.keyOrigin
- resource.keyType
- resource.name
  - Format: projects/PROJECT_ID/serviceAccounts/UNIQUE_ID/keys/KEY_ID

Example custom organization policies for common use cases

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

For more information about CEL macros available for use in custom constraint conditions, see Common Expression Language.

Description	Constraint syntax
Disable service account creation.	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.disableServiceAccountCreation resourceTypes: - iam.googleapis.com/ServiceAccount methodTypes: - CREATE condition: "True" actionType: DENY displayName: Deny all service account creation.
Disable service account key creation.	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.disableServiceAccountKeyCreation resourceTypes: - iam.googleapis.com/ServiceAccountKey methodTypes: - CREATE condition: "resource.keyType == USER_MANAGED && resource.keyOrigin == GOOGLE_PROVIDED" actionType: DENY displayName: Deny all service account key creation.
Disable service account key upload.	name: organizations/`ORGANIZATION_ID`/customConstraints/custom.disableServiceAccountKeyUpload resourceTypes: - iam.googleapis.com/ServiceAccountKey methodTypes: - CREATE condition: "resource.keyType == USER_MANAGED && resource.keyOrigin == USER_PROVIDED" actionType: DENY displayName: Deny all service account key uploads.

Description

Constraint syntax

Disable service account creation.

    name: organizations/ORGANIZATION_ID/customConstraints/custom.disableServiceAccountCreation
    resourceTypes:
    - iam.googleapis.com/ServiceAccount
    methodTypes:
    - CREATE
    condition: "True"
    actionType: DENY
    displayName: Deny all service account creation.

Disable service account key creation.

    name: organizations/ORGANIZATION_ID/customConstraints/custom.disableServiceAccountKeyCreation
    resourceTypes:
    - iam.googleapis.com/ServiceAccountKey
    methodTypes:
    - CREATE
    condition: "resource.keyType == USER_MANAGED && resource.keyOrigin == GOOGLE_PROVIDED"
    actionType: DENY
    displayName: Deny all service account key creation.

Disable service account key upload.

    name: organizations/ORGANIZATION_ID/customConstraints/custom.disableServiceAccountKeyUpload
    resourceTypes:
    - iam.googleapis.com/ServiceAccountKey
    methodTypes:
    - CREATE
    condition: "resource.keyType == USER_MANAGED && resource.keyOrigin == USER_PROVIDED"
    actionType: DENY
    displayName: Deny all service account key uploads.

What's next

See Introduction to the Organization Policy Service to learn more about organization policies.
Learn more about how to create and manage organization policies.
See the full list of predefined organization policy constraints.