Whether to enable encryption at rest. If the encrypt_at_rest block is not provided then this defaults to false. Enabling encryption on new domains requires an engine_version of OpenSearch_X.Y or Elasticsearch_5.1 or greater.
KMS key ARN to encrypt the Elasticsearch domain with. If not specified then it defaults to using the aws/es service KMS key. Note that KMS will accept a KMS key ID but will return the key ARN. To prevent the provider detecting unwanted changes, use the key ARN instead.