aws-lambda-event-sources: S3EventSource Requires Bucket, but only needs an IBucket

[Styerp]

Describe the bug

I want to use an externally created bucket as an event notification source for a lambda

Expected Behavior

An IBucket can be used as the notification source

Current Behavior

Type errors. An IBucket cannot be assigned to a Bucket.

Reproduction Steps

import * as core from "aws-cdk-lib";
import * as event_sources from "aws-cdk-lib/aws-lambda-event-sources";
import * as s3 from "aws-cdk-lib/aws-s3";

const app = new core.App()
const ibucket = s3.Bucket.fromBucketName(app, "IBucket", "IBucket");
const eventSource = new event_sources.S3EventSource(ibucket, {events: [s3.EventType.OBJECT_CREATED]})

TS2345: Argument of type 'IBucket' is not assignable to parameter of type 'Bucket'.

Possible Solution

Since addEventNotification is the only method used by S3EventSource and is available on an IBucket, I think it should be safe to loosen the type restriction to IBucket.

Coercing the type and deploying works.

Additional Information/Context

No response

CDK CLI Version

2.40.0

Framework Version

No response

Node.js Version

16

OS

OSX

Language

Typescript

Language Version

No response

Other information

No response

[peterwoodworth]

Thanks for this request, it looks to me like it's not necessary to only allow a Bucket, and that having IBucket here would be fine. However, this would cause issues when adding a notification for a LambdaDestination, as that requires having the Bucket construct

However there is already an existing check for this:

aws-cdk/packages/@aws-cdk/aws-s3-notifications/lib/lambda.ts

Lines 17 to 20 in c164a49

	if (!(bucket instanceof Construct)) {
	throw new Error(`LambdaDestination for function ${Names.nodeUniqueId(this.fn.permissionsNode)} can only be configured on a
	bucket construct (Bucket ${bucket.bucketName})`);
	}

If properly documented we could be able to allow for imported buckets to be used here to allow for more use cases

I am marking this issue as p2, which means that we are unable to work on this immediately.

[casyalex]

+1

[bferdousi]

+1

[MacHu-GWU]

Tested on 2.81.0, this is not fixed yet. In case you are having the same issue, here's my alternative solution:

        bucket = s3.Bucket.from_bucket_attributes(
            self,
            "ImportedBucket",
            bucket_arn=f"arn:aws:s3:::{self.env.s3dir_source.bucket}",
        )

        use latest
        bucket.add_event_notification(
            s3.EventType.OBJECT_CREATED,
            s3_notifications.LambdaDestination(
                self.lambda_func_mapper[self.env.lbd_s3sync.name][KEY_FUNC],
            ),
            s3.NotificationKeyFilter(
                prefix=f"{self.env.s3dir_source.key}",
            ),
        )

        use alias
        bucket.add_event_notification(
            s3.EventType.OBJECT_CREATED,
            s3_notifications.LambdaDestination(
                lambda_.Function.from_function_attributes(
                    self,
                    f"LambdaAliasAttribute{self.env.lbd_s3sync.short_name_camel}",
                    function_arn=self.lambda_func_mapper[self.env.lbd_s3sync.name][KEY_ALIAS].function_arn,
                    same_environment=True,
                ),
            ),
            s3.NotificationKeyFilter(
                prefix=f"{self.env.s3dir_source.key}",
            ),
        )

[tim-finnigan]

This appears to be a duplicate of this older issue: #4323. I'm going to close this in order to consolidate issues.

[github-actions]

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