(custom-resources): Provider function is throwing "Error: return values from user-handlers must be JSON objects. got: ""

[mrlikl]

Describe the bug

Hello team,

I am seeing the error Error: return values from user-handlers must be JSON objects. got: "" recently while using the Provider construct of aws-cdk-lib/custom-resources. Checking the cloudwatch logs of the request, I see that this is the return value sent back from the oneventhandler lambda fn.

{
    $metadata: {
      httpStatusCode: 200,
      requestId: 'xxxx',
      attempts: 1,
      totalRetryDelay: 0
    },
    ExecutedVersion: '$LATEST',
    Payload: {},
    StatusCode: 200
  }

I see that there was a change recently in parseJsonPayload function from const text = payload.toString(); to let text = new TextDecoder().decode(Buffer.from(payload));.

Expected Behavior

Provider fn to return empty values/success

Current Behavior

Provider function is throwing "Error: return values from user-handlers must be JSON objects. got: ""

Reproduction Steps

Not sure of the reproduction steps here. Although I do not see any return from the event lambda.
This works fine if the return logged is "" like

{
    $metadata: {
      httpStatusCode: 200,
      requestId: 'xxxx',
      attempts: 1,
      totalRetryDelay: 0
    },
    ExecutedVersion: '$LATEST',
    Payload: "",
    StatusCode: 200
  }

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.87.0

Framework Version

No response

Node.js Version

18.16

OS

mac

Language

Typescript

Language Version

No response

Other information

No response

[peterwoodworth]

Logging the return as "" probably works because that is a falsy value, as opposed to {}. Looks like this was an edge case that went unaccounted for. Does this break you and prevent you from being able to properly upgrade without making changes @mrlikl?

[mrlikl]

I do not have direct access to the onevent lambda code. The payload data is from the provider lambda's logs.

[jalvinake]

I am also having this exact error. I am unable to upgrade our production system due to it.

[MrArnoldPalmer]

@jalvinake @mrlikl can you provide an example of what your handler is returning (I know you said you don't have access to the handler code is it a CR in aws-cdk-lib?)? I'm pretty sure we can just change the logic to something similar to the change we made in AwsCustomResource, but I want to make sure I have a good test here.

[rtfinspace]

we recently migrated to cdkv2, Provider lambda errored with this return response object .
{
$metadata: {
httpStatusCode: 200,
requestId: 'xxxx',
attempts: 1,
totalRetryDelay: 0
},
ExecutedVersion: '$LATEST',
Payload: {},
StatusCode: 200
}

Provider lambda used nodejs18 as runtime. Having issues specifically with this.
There are other packages with exact same implementation, where Provider lambda doesnt have any issues, uses nodejs14 as runtime. Not sure if the error is because of nodejs18 ?

[github-actions]

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