(rds): copy_tags_to_snapshot option missing from DatabaseCluster class

[aktungmak]

The Question

The class aws_cdk.aws_rds.DatabaseInstance provides the keyword argument copy_tags_to_snapshot in its constructor, to ensure that snapshots are created with the same tags as the database.

However, the class aws_cdk.aws_rds.DatabaseCluster does not offer this option and this means that snapshots are created without tags.

To verify this was the problem, I deployed the following stack and then checked the "Backup" section of the AWS console
and I could see that the option "Copy tags to snapshots" was set to "Disabled".

from aws_cdk import (
    aws_ec2 as ec2,
    aws_rds as rds,
    core,
)

class TestStack(core.Stack):
    def __init__(self, scope: core.Construct, id: str, **kwargs) -> None:
        super().__init__(scope, id, **kwargs)

        self.cluster()

    def cluster(self):
        return rds.DatabaseCluster(
            self,
            "cluster",
            engine=rds.DatabaseClusterEngine.aurora_postgres(
                version=rds.AuroraPostgresEngineVersion.VER_11_8
            ),
            instance_props=rds.InstanceProps(
                vpc=ec2.Vpc.from_lookup(
                    self, "vpc", vpc_name="vpc-1"
                ),
                instance_type=ec2.InstanceType.of(
                    ec2.InstanceClass.BURSTABLE3, ec2.InstanceSize.MEDIUM
                ),
            ),
        )

Expectation

The keyword argument copy_tags_to_snapshot is available in the constructor of aws_cdk.aws_rds.DatabaseCluster and it has the same behaviour as inaws_cdk.aws_rds.DatabaseInstance.

Environment

• CDK CLI Version: 1.78.0 (build 2c74f4c)
• Module Version: 1.78.0
• Node.js Version: v14.11.0
• OS: macos Catalina 10.15.7 (19H15)
• Language: Python

[skinny85]

Thanks for opening the issue @aktungmak . Any chance of creating a PR adding this property to the InstanceProps interface? Here's our "Contributing" guide: https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md#gitpod

Thanks,
Adam

[aktungmak]

Hi Adam! While doing some further searching on this subject, I discovered that this is actually not supported in CloudFormation (https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbcluster.html) and indeed someone has already created a feature request (aws-cloudformation/cloudformation-coverage-roadmap#238).

If I understand correctly, CDK can only use features that exist in CloudFormation so this cannot be resolved until the feature is added to CloudFormation. Or is there another way around this?

[skinny85]

Hey @aktungmak ,

in theory, the could provide that functionality with a CloudFormation Custom Resource. However, we usually reserve that for bigger features, as it requires deploying a Lambda function along with your Stack, which is a pretty large and expensive abstraction 🙂. Usually we don't do that for single properties like these.

I'll add the needs-cfn label to indicate this is waiting for CloudFormation support.

[Bryconc]

Hi all,

Looks like the property CopyTagsToSnapshot has recently been added to the CloudFormation resource (https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbcluster.html#cfn-rds-dbcluster-copytagstosnapshot).

(aws-cloudformation/cloudformation-coverage-roadmap#238 (comment))

Does this mean this is ready for implementation?

[skinny85]

Yep @Bryconc. PRs are very much welcome, as always! https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md

[blimmer]

It looks like this property is available on Cluster now, so I think this issue can be closed: https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_rds.DatabaseClusterProps.html#copytagstosnapshot

[skinny85]

Yep, thanks @blimmer!

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