Aws-cdk: Fix EventPattern to be usable in CloudWatch Events Rules

[0xdabbad00]

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• I'm submitting a ...

  • [X] :beetle: bug report
  • [ ] :rocket: feature request
  • [ ] :books: construct library gap
  • [ ] :phone: security issue or vulnerability => Please see policy
  • [ ] :question: support request => Please see note at the top of this template.

• What is the current behavior?
  If the current behavior is a :beetle:bug:beetle:: Please provide the steps to reproduce
  I can create a CloudWatch Event Rule that uses a Schedule as follows:

new events.Rule(this, "heartbeat_rule", {
      schedule: events.Schedule.expression("rate(30 minutes)"),
...
    });

But if I try to do that with an EventPattern, it is undefined. Example:

new events.Rule(this, "heartbeat_rule", {
      eventPattern: events.EventPattern.source([...]),
...
    });

events.EventPattern is undefined.

• What is the expected behavior (or behavior of feature suggested)?
  My expectation is that I should be able to use EventPattern as described in the docs here: https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-events.Rule.html

I can't figure out how to use an EventPattern though. I think maybe because it is an Interface, but nothing seem to implement that Interface.

• What is the motivation / use case for changing the behavior or adding this feature?
  I want to create a CloudWatch Events Rule to receive GuardDuty events.

• Please tell us about your environment:

  • CDK CLI Version: 0.35.0
  • Module Version: aws-events
  • OS: [all | Windows 10 | OSX Mojave | Ubuntu | etc... ]
  • Language: [all | TypeScript | Java | Python ]

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc)

[rix0rrr]

new events.Rule(this, "heartbeat_rule", {
      eventPattern: events.EventPattern.source([...]),
...
    });

I'm not even sure how the proposed code compiles. EventPattern is an interface, not a class, so this can't work in either TypeScript or JavaScript.

The correct syntax would be:

new events.Rule(this, "heartbeat_rule", {
      eventPattern: {
         source: ['...']
      }, 
    });

I will admit it's not super obvious that one uses a class constructor and the other one uses an object literal.

[rix0rrr]

Please reopen if you have further questions or remarks.