Warning when creating multiple aws_s3_bucket_notification resources on the same bucket

[njlr]

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Description

When creating multiple aws_s3_bucket_notification resources on the same bucket, it would be great if Terraform could produce a warning, since this is invalid and can lead to confusing bugs.

New or Affected Resource(s)

• aws_s3_bucket_notification

Potential Terraform Configuration

This is invalid:

resource "aws_s3_bucket_notification" "foo_writes" {
  bucket = aws_s3_bucket.foo.id

  lambda_function {
    lambda_function_arn = aws_lambda_function.foo.arn
    events              = [ "s3:ObjectCreated:*" ]
  }
}

resource "aws_s3_bucket_notification" "foo_writes2" {
  bucket = aws_s3_bucket.foo.id

  lambda_function {
    lambda_function_arn = aws_lambda_function.bar.arn
    events              = [ "s3:ObjectCreated:*" ]
  }
}

Terraform should warn the user.

This is what should be done instead:

resource "aws_s3_bucket_notification" "foo_writes" {
  bucket = aws_s3_bucket.foo.id

  lambda_function {
    lambda_function_arn = aws_lambda_function.foo.arn
    events              = [ "s3:ObjectCreated:*" ]
  }

  lambda_function {
    lambda_function_arn = aws_lambda_function.bar.arn
    events              = [ "s3:ObjectCreated:*" ]
  }
}

[bflad]

Hi @njlr 👋 Thank you for raising this feature request. Long term, this is likely something we do want to address more holistically for Terraform resources. We have been consolidating these types of requests into #14394 as a single tracking issue for the Terraform AWS Provider and hashicorp/terraform-plugin-sdk#224 in the Terraform Plugin SDK. Please feel free to 👍 react and subscribe to them for further updates and discussions.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!