Change on non-computed attributes does not properly delegate to data source

[synthdnb]

I made small terraform file to reproduce this issue.

resource "aws_route53_record" "test" {
  zone_id = "ZONE_ID"
  name    = "test1.domain.com"
  type    = "A"
  ttl     = "300"
  records = ["1.2.3.4"]
}

data "template_file" "tpl" {
  template = "$${url}"

  vars {
    url = "${aws_route53_record.test.name}"
  }
}

resource "aws_s3_bucket_object" "object" {
  bucket  = "SOME_BUCKET_NAME"
  key     = "SOME_KEY"
  content = "${data.template_file.tpl.rendered}"
}

When I change name on aws_route53_record.test to test2.domain.com, but template_file.tpl fails detect change on first apply. It detects change on next apply.

Using aws_route53_record.test.fqdn instead of name solves the problem in this case. It seems that name reads value from previous state since it is not a computed attribute, and fqdn works well since it is computed attribute and defers evaluation until apply.

Is this behavior intended? Even if this behavior is intended, I think enhancing documentation about this case may help everyone a lot.

[jbardin]

Hi @synthdnb,

Thanks for the excellent bug report.
I think the issue might be that name forces a new resource, so the existing resource referenced when the datasource is refreshed is technically unchanged, and hasn't yet been marked as deposed. You might be able to work around this for now by using depends_on in the template_file, which forces a datasource to be refreshed after its dependencies, which should pick up the new resource.

[apparentlymart]

The quirky behavior here would be addressed by the lifecycle change proposed in #17034.

[hashibot]

Hello! 🤖

This issue seems to be covering the same problem or request as #17034, so we're going to close it just to consolidate the discussion over there. Thanks!

[ghost]

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