Overview

CloudFormation has a different way of responding to most events due to the way stacks execute.

It is best to catch all errors and ensure the correct response is sent to the pre-signed URL that comes with the event.

To make this easier, a wrapper exists to allow the creation of custom resources without having to handle that.

Sample Function

This sample will safely 'Echo' back anything given into the Echo parameter within the Custom Resource call.

import (
    "context"
    "fmt"

    "github.com/aws/aws-lambda-go/cfn"
    "github.com/aws/aws-lambda-go/lambda"
)

func echoResource(ctx context.Context, event cfn.Event) (physicalResourceID string, data map[string]interface{}, err error) {
    v, _ := event.ResourceProperties["Echo"].(string)

    data = map[string]interface{} {
        "Echo": v,
    }

    return
}

func main() {
	lambda.Start(cfn.LambdaWrap(echoResource))
}