Tagging EnabledControl resources in AWS Control Tower

You can add tags to EnabledControl resources by means of AWS CloudFormation templates, through the AWS Control Tower console, and by calling the AWS Control Tower APIs.

Required permissions

When you configure resource tags with CloudFormation, you must add the new ListTagsforResource IAM permission to the policy for the customer-managed role that you use to update your controls. If you do not add the permission, the CloudFormation template may have the tags, but AWS CloudFormation cannot see them without the ability to call ListTagsforResource. If you already have created a role that updates your AWS Control Tower landing zone, that role probably has this permission in place already, because the same permission is required to view tags associated with the landing zone resource.

Step 1: Add the permissions

To tag a resource, update a tag, and enable proper drift reporting, three permissions are required, as shown in the example that follows.

{
	"Version": "2012-10-17",
	"Statement": [
		{
			"Sid": "VisualEditor0",
			"Effect": "Allow",
			"Action": [
				"controltower:TagResource",
				"controltower:ListTagsForResource",
				"controltower:UntagResource"
			],
			"Resource": "*"
		}
	]
}

CloudFormation drift

If you do not add the proper permissions, you can experience some side-effects that we refer to as false positive or false negative CloudFormation drift. During CloudFormation drift, the Detect drift command in the AWS CloudFormation console may not give reliable results. You also can encounter these side effects if you modify your CloudFormation resource outside the AWS CloudFormation console.

When you experience false positive CloudFormation drift, the AWS CloudFormation console shows a Modified status (drifted) for a resource, although you are not aware of making any modifications. In this situation, the status means that you have not added the ListTagsforResource permission. When the permission is not present in the role, the ReadHandler cannot read the tags. AWS CloudFormation returns an error, because it cannot tell whether the resource actually was modified. The error is surfaced as Modified status.

When you experience false negative drift the CloudFormation console shows a resource as unmodified, when in fact, it has been modified. This situation means that the AWS Control Tower EnabledControl resource has tags, but CloudFormation cannot retrieve those tags. In this case, two things must have occurred: the resource has been modified outside AWS CloudFormation, which is not a recommended practice, and also the ListTagsforResource permission was not added to the policy.

Step 2. Add the tags to the resource

Here is an example CloudFormation resource template with tags added.

AWSTemplateFormatVersion: 2010-09-09
Resources:
  myEnabledControlTest:
    Type: 'AWS::ControlTower::EnabledControl'
    Properties:
      ControlIdentifier: 'arn:aws:controltower:us-west-2::control/ZTCMZEXAMPLE'
      TargetIdentifier: 'arn:aws:organizations::012345678901:ou/o-exampleou/ou-xxxx-f35g82v9'
      Tags:
        - Key: "K1"
          Value: "V1"
      Parameters:
        - Key: AllowedRegions
          Value:
            - us-west-2
            - us-west-1
            - us-east-1

For more information, see EnabledControl in the AWS CloudFormation User Guide.