Feature: SNS Event FilterPolicyScope attribute

[mustafa-sadiq]

Issue #, if available

N/A

Description of changes

Adds the FilterPolicyScope attribute to the SNS Subscription created for a SNS function event source.
This attribute is supported by cloudformation:
https://aws.amazon.com/blogs/compute/introducing-payload-based-message-filtering-for-amazon-sns/

If you try to deploy a function with event

Events:
  NotificationTopic:
    Type: SNS
    Properties:
      Topic: !Ref MySNSTopic
      Region: region
      FilterPolicy:
        store:
        - example_corp
        event:
        - anything-but: order_cancelled
        customer_interests:
        - rugby
        - football
        - baseball
        price_usd:
        - numeric:
          - '>='
          - 100
      FilterPolicyScope: MessageAttributes

sam deploy gives this output

Error: Failed to create changeset for the stack: sam-hello-world, ex: Waiter ChangeSetCreateComplete failed: Waiter encountered a terminal failure state: For expression "Status" we matched expected path: "FAILED" Status: FAILED. Reason: Transform AWS::Serverless-2016-10-31 failed with: Invalid Serverless Application Specification document. Number of errors found: 1. Resource with id [HelloWorldFunctionNotificationTopic] is invalid. property FilterPolicyScope not defined for resource of type SNS

Description of how you validated changes

I deployed a transformed template with the FilterPolicyScope: MessageAttributes added.

Checklist

• Adheres to the development guidelines
• Add/update transform tests
  • Using correct values
  • Using wrong values
• Add/update integration tests

Examples?

Deploy a Function with a SNS event source and add property:
FilterPolicyScope: MessageAttributes

Please reach out in the comments if you want to add an example. Examples will be
added to sam init through aws/aws-sam-cli-app-templates.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[GavinZZ]

Thanks for opening the PR. The changes look good. I have one question before I approve. I see that FilterPolicyScope supports two possible value, MessageAttributes or MessageBody. Is there any reason we aren't testing MessageBody as an input?

edit: I meant integration test, not transform test.

[mustafa-sadiq]

Thanks for opening the PR. The changes look good. I have one question before I approve. I see that FilterPolicyScope supports two possible value, MessageAttributes or MessageBody. Is there any reason we aren't testing MessageBody as an input?

The test will pass no matter what I change the value to. I set it to InvalidValue and it would pass through. I am not sure how to set an integration test so that CloudFormation will fail so I will leave that up to the team.

[GavinZZ]

Thanks for the contribution!!

[mustafa-sadiq]

thank you @hoffa and @GavinZZ! I am new to open-source and appreciate the guidance and reviews! <3