How to integrate new cdk stack with existed aws EventBridge (EventTarget)

Question

Since the resources on AWS have been created by manual on console. e.g. Rule, EventBus, APIDestination (Target). Means these resource doesn't provide any cdk code.

Point is I want to add more Rule with existing EventBus and APIDestination (Target)**. Then customize input_transformer in targets within cdk code.

from aws_cdk import aws_events as events, aws_events_targets as targets

class TheDestinedLambdaStack(core.Stack):

    def __init__(self, scope: core.Construct, id: str, **kwargs) -> None:
        super().__init__(scope, id, **kwargs)

        new_rule = events.Rule(
            self, 
            "rule",
            event_pattern=events.EventPattern(),
            event_bus=events.from_event_bus_arn(), # imported
            targets=#APIDestination with params and transformer, dont know method ???
        )

It's possible to implement this?
or anyone know which method of EventTarget able to import existed resource to cdk?

Docs: https://docs.aws.amazon.com/cdk/api/v2/python/aws_cdk.aws_events/EventBus.html

Answer 1

The L1 CfnRule construct can create a new Rule targeting an existing API Destination and custom bus. It can also optionally apply input transforms:

events.CfnRule(
    self,
    "Rule",
    event_bus_name="my-bus-name",
    event_pattern={"source": ["cdk-test"]},
    targets=[
        events.CfnRule.TargetProperty(
            arn="arn:aws:events:us-east-1:xxxx:api-destination/xxxxxxxx",
            id="foo_rule",
            role_arn="arn:aws:iam::xxxxx:role/xxxxxxxxx",
            input_transformer=events.CfnRule.InputTransformerProperty(
                input_paths_map={"detail-type": "$.detail-type"},
                input_template=json.dumps(
                    {
                        "transformed": '{"name": "DETAIL_TYPE", "value": <detail-type>}'
                    }
                ),
            ),
        )
    ],
)