SNS: payload-based message filtering

[brennanho]

Describe the feature

AWS introduced payload-based message filtering: https://aws.amazon.com/blogs/compute/introducing-payload-based-message-filtering-for-amazon-sns/. Would be awesome to see support for this in CDK.

Use Case

Filtering out messages by payload attributes. Often, SNS owners from away teams do not supply the sufficient message attributes to filter out messages. This change would allow SNS subscribers (SQS subscribing to SNS in my case) to filter messages regardless of whether the SNS owner has configured any message attributes.

Proposed Solution

Have the option to choose FilterPolicyScope when subscribing to an SNS topic i.e. either MessageBody or MessageAttributes. See: https://docs.aws.amazon.com/sns/latest/dg/sns-message-filtering.html. I was thinking to add filterPolicyScope to the SubscriptionFilter class and then being able to switch filterPolicyScope to either MessageBody or MessageAttributes.

Before:

  Topic.fromTopicArn(
      myStack,
      "myStackId",
      "arn:aws:sns:us-east-1:..."
  ).addSubscription(new SqsSubscription(myLambda.inputQueue, { filterPolicy: {...} }));

After:

  Topic.fromTopicArn(
      myStack,
      "myStackId",
      "arn:aws:sns:us-east-1:..."
  ).addSubscription(new SqsSubscription(myLambda.inputQueue, { filterPolicyScope: "MessageBody", filterPolicy: {...} }));

Other Information

Links

• SNS Message Filtering: https://docs.aws.amazon.com/sns/latest/dg/sns-message-filtering.html
• Payload-based Message Filtering blog post: https://aws.amazon.com/blogs/compute/introducing-payload-based-message-filtering-for-amazon-sns/
• Example Filter Policies: https://docs.aws.amazon.com/sns/latest/dg/example-filter-policies.html
• CDK Docs: https://docs.aws.amazon.com/cdk/api/v1/docs/@aws-cdk_aws-sns.SubscriptionFilter.html

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.38.1 (aws-cdk-lib)

Environment details (OS name and version, etc.)

MacOS 12.3.1

[peterwoodworth]

Thanks for the request, it seems like CloudFormation support should be live already with this feature so we should be good to start working on it.

Edit: We need the CfnSpec to merge this update first before we can merge the PR. Thanks for the contribution!

[brennanho]

Thanks for the request, it seems like CloudFormation support should be live already with this feature so we should be good to start working on it.

I can create a PR for this if the effort is small. Do you know where the changes would need to be made?

[brennanho]

PR: #23108

[github-actions]

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