{
 "actionState": "Failed",
 "stateUpdateTimestamp": 1558142246126,
 "notificationResource": "arn:aws:sns:us-east-1:5847563209:<myTopic>",
 "publishedMessage": null,
 "error": "null (Service: AWSKMS; Status Code: 400; Error Code: AccessDeniedException; Request ID: 6b7806a6-2c16-4582-9ecd-05100161746e)"

{
  "Sid": "Allow CloudWatch to use the key",
  "Effect": "Allow",
  "Principal": {
      "Service": "cloudwatch.amazonaws.com"
  },
  "Action": [
      "kms:GenerateDataKey",
      "kms:Decrypt"
  ],
  "Resource": "*"
}