[s3-notifications] s3 notification to lambda functions not working with existing Buckets

Using S3EventSource to create a lambda triggered by S3 Object_Created events of a bucket which already exists. If you follow the instruction in the documentation (https://docs.aws.amazon.com/cdk/api/latest/docs/aws-lambda-event-sources-readme.html#s3) the resources cannot be created due to the following type mismatch:

Argument of type 'IBucket' is not assignable to parameter of type 'Bucket'.
  Type 'IBucket' is missing the following properties from type 'Bucket': autoCreatePolicy, lifecycleRules, notifications, metrics, and 33 more.

Reproduction Steps

1. Create a Function with “@aws-cdk/aws-lambda”
2. Add EventSource using S3EventSource (“@aws-cdk/aws-lambda-event-sources”) of external bucket (“@aws-cdk/aws-s3”)

const function = new Function(stack, 'SomeFunction', { ... })
const bucket = Bucket.fromBucketName(stack, 'SomeBucket', bucketName)
function.addEventSource(
  new S3EventSource(bucket, {
      events: [EventType.OBJECT_CREATED]
})
)

What did you expect to happen?

I expected that creating a S3/Lambda trigger would be very easy with “@aws-cdk/aws-lambda-event-sources” without type errors. The deployment of such easy things should be so easy. This is not the first time I have experienced problems with types or functions that do not allow to do what they should be able to do… I don’t understand why the Bucket returned by Bucket.fromBucketName is something different from new Bucket(). Both Bucket(s) are from the same lib and nevertheless have different types.

What actually happened?

Type Errors during development and deployment

Environment

• **CLI Version : “aws-cdk”: “1.60.0”,
• **Node.js Version: 12
• **OS : mac/ linux
• **Language (Version): TypeScript (3.9.3)

Other

/Volumes/Workspace/project/node_modules/@aws-cdk/aws-lambda-event-sources/lib/s3.ts:31
      this.bucket.addEventNotification(event, new notifs.LambdaDestination(target), ...filters);
                          ^
TypeError: this.bucket.addEventNotification is not a function
    at S3EventSource.bind (/Volumes/Workspace/project/node_modules/@aws-cdk/aws-lambda-event-sources/lib/s3.ts:31:19)
    at Function.addEventSource (/Volumes/Workspace/project/node_modules/@aws-cdk/aws-lambda/lib/function-base.ts:309:12)
    at Object.<anonymous> (/Volumes/Workspace/project/cdk/functions/somefunction.ts:33:14)
    at Module._compile (internal/modules/cjs/loader.js:959:30)
    at Module.m._compile (/Volumes/Workspace/project/node_modules/ts-node/src/index.ts:858:23)
    at Module._extensions..js (internal/modules/cjs/loader.js:995:10)
    at Object.require.extensions.<computed> [as .ts] (/Volumes/Workspace/project/node_modules/ts-node/src/index.ts:861:12)
    at Module.load (internal/modules/cjs/loader.js:815:32)
    at Function.Module._load (internal/modules/cjs/loader.js:727:14)
    at Module.require (internal/modules/cjs/loader.js:852:19)

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This is 🐛 Bug Report

[ThomasKiec]

@iliapolo Yes we can close this one as duplicate

[iliapolo]

@ThomasKiec We already have an issue for this: https://github.com/aws/aws-cdk/issues/2004.

Can you look it over and let us know if its ok to close this one as duplicate?