[E3002] CommaDelimitedList parameter value is not considered a list

cfn-lint version: 0.61.4

I am receiving the following error:

E3002: Property Subnets should be of type List or Parameter should be a list for resource LoadTestRule

This occurs when using a CloudFormation SSM Parameter with the type AWS::SSM::Parameter::Value<CommaDelimitedList>, where the parameter value is assigned to a Property that expects a list of Strings. However, this error does not occur when the parameter’s type is changed to AWS::SSM::Parameter::Value<List<String>>. According to the CloudFormation Parameters documentation, these two types appear to be interchangeable.

This issue persists after updating both cfn-lint and the spec files.

This example produces the error on the Subnets property. Changing the parameter’s type to AWS::SSM::Parameter::Value<List<String>> does not.

LoadTestContainerSubnetParameter:
  Type: AWS::SSM::Parameter::Value<CommaDelimitedList>
  Description: location of SSM parameter value, containing list of public subnets

# ...

LoadTestRule:
  Type: AWS::Events::Rule
  Properties:
    Description: Invoke nightly
    Name: !Sub '${ApplicationName}-load-test'
    ScheduleExpression: cron(0 3 ? * MON-FRI *)
    State: ENABLED
    Targets:
      - Arn: !GetAtt LoadTestEcsCluster.Arn
        RoleArn: !GetAtt LoadTestSchedulerRole.Arn
        Id: !Sub '${ApplicationName}-load-test'
        EcsParameters:
          EnableExecuteCommand: false
          LaunchType: FARGATE
          NetworkConfiguration:
            AwsVpcConfiguration:
              AssignPublicIp: ENABLED
              SecurityGroups:
                - !GetAtt ClusterSecurityGroup.GroupId
              Subnets: !Ref LoadTestContainerSubnetParameter
          TaskCount: 1
          TaskDefinitionArn: !Ref LoadTestTaskDefinition

[kddejong]

AWS:DynamoDB::Table I’ve been trying to keep an eye on this one. It seems like some things are changing with the resource that has resulted in this. It was coming from the resource spec itself and how it was defined which is why you could see an issue if you were running cfn-lint --update-specs. I was about to patch the issue when I noticed that the .Json property type no longer existed. I am continuing to monitor this.

[kddejong]

Merged with #2320 released with v0.61.5