aws-lambda: default values discrepancies between TypeScript and Web documentation

[Serede]

https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-lambda.EventSourceMappingOptions.html

There seems to be some inconsistencies in the default values specified for the EventSourceMappingOptions interface between TypeScript source and Web versions of the CDK package documentation.

At least, these are the ones that I found:

• maxRecordAge
  • Source says @default Duration.days(7).
  • Web says default: infinite or until the record expires.
  • Empirical default value: -1 (infinite)
• retryAttempts
  • Source says @default 10000.
  • Web says default: infinite or until the record expires.
  • Empirical default value: -1 (infinite)

Please make default values consistent between TypeScript and Web versions of the documentation as many of us rely on TypeScript LSP for documentation.

---

This is a 📕 documentation issue

[nija-at]

Hi @Serede -

You are comparing the wrong artifacts. The typescript source you linked is of StreamEventSourceProps and here is the documentation for it - https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-lambda-event-sources.StreamEventSourceProps.html.

[Serede]

@nija-at you are right, thank you for clarifying. I still believe there is an issue with the default values, though. Let me explain better.

I created a DynamoEventSource like this:

    const testrunsEventSource = new DynamoEventSource(testrunsTable, {
      batchSize: 100,
      onFailure: new SqsDlq(deadLetterQueue),
      startingPosition: StartingPosition.TRIM_HORIZON,
    });

I see the constructor for DynamoEventSource takes DynamoEventSourceProps as second argument, which is itself an extension of the StreamEventSourceProps you just linked. There, the default values for StreamEventSourceProps are:

• maxRecordAge. Type: Duration (optional, default: Duration.days(7))
• retryAttempts. Type: number (optional, default: 10000)

So far so good. However, when I deployed the stack to CloudFormation, both properties took value -1 (infinite).

I had to change the code like this to make them finite:

    const testrunsEventSource = new DynamoEventSource(testrunsTable, {
      batchSize: 100,
      onFailure: new SqsDlq(deadLetterQueue),
      startingPosition: StartingPosition.TRIM_HORIZON,
      maxRecordAge: Duration.minutes(10),
      retryAttempts: 10,
    });

I reported the issue because I believe this can cause unintended behavior to other users as it did for me.

[nija-at]

@Serede - You are indeed correct. The defaults documented are incorrect.

I have submitted a fix for this - #14562

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