TypeSet count (.#) not being removed when d.Set(nil) is used w/ 0.12 SDK

[rileykarson]

Terraform Version

Running a Google provider acceptance test with 
github.com/hashicorp/terraform v0.12.0-alpha4.0.20190226230829-c2f653cf1a35 vendored.

master is in this state.

Terraform Configuration Files

resource "google_compute_disk" "test1" {
  name = "%s"
  zone = "us-central1-a"
  size = 10
}

resource "google_compute_instance" "test" {
  name         = "%s"
  machine_type = "f1-micro"
  zone         = "us-central1-a"

  lifecycle {
    ignore_changes = [
      "attached_disk",
    ]
  }

  boot_disk {
    initialize_params {
      image = "debian-cloud/debian-9"
    }
  }

  network_interface {
    network = "default"
  }
}

resource "google_compute_attached_disk" "test" {
  disk     = "${google_compute_disk.test1.self_link}"
  instance = "${google_compute_instance.test.self_link}"
}

Followed by

resource "google_compute_disk" "test1" {
  name = "%s"
  zone = "us-central1-a"
  size = 10
}

resource "google_compute_instance" "test" {
  name         = "%s"
  machine_type = "f1-micro"
  zone         = "us-central1-a"

  lifecycle {
    ignore_changes = [
      "attached_disk",
    ]
  }

  boot_disk {
    initialize_params {
      image = "debian-cloud/debian-9"
    }
  }

  network_interface {
    network = "default"
  }
}

Expected Behavior

Terraform should see an empty list of users for the disk as the attachment was removed.

Actual Behavior

STATE:

google_compute_disk.test1:
  ID = tf-test-disk-4936674271243668487
  provider = provider.google
  creation_timestamp = 2019-02-27T02:15:50.880-08:00
  description = 
  image = 
  label_fingerprint = 42WmSpB8rSM=
  last_attach_timestamp = 2019-02-27T02:16:19.543-08:00
  last_detach_timestamp = 2019-02-27T02:16:31.576-08:00
  name = tf-test-disk-4936674271243668487
  project = hc-terraform-testing
  self_link = https://www.googleapis.com/compute/v1/projects/hc-terraform-testing/zones/us-central1-a/disks/tf-test-disk-4936674271243668487
  size = 10
  snapshot = 
  source_image_id = 
  source_snapshot_id = 
  type = pd-standard
  users.# = 1
  zone = us-central1-a

leading to

 Error: errors during apply: Unknown user "" of disk "https://www.googleapis.com/compute/v1/projects/hc-terraform-testing/zones/us-central1-a/disks/tf-test-disk-4936674271243668487"

because of https://github.com/terraform-providers/terraform-provider-google/blob/master/google/resource_compute_disk.go#L752

Steps to Reproduce

make testacc TEST=./google TESTARGS='-run=TestAccComputeAttachedDisk_basic'

[jbardin]

Hi @rileykarson,

Thanks for the detail here. This test has some interesting interactions that I haven't completely sorted out. I'm just gong to bullet a few things here to investigate:

• The attached_disk attribute is not computed, but it is set during Read, which is chained from Create. Since it's not computed, plus the values aren't planned at all, it cannot be reliably set during apply.
• The .# count attribute is used in the source, which is an implementation detail that shouldn't appear in provider code.
• A number of other attributes are set during apply which weren't set in the plan.

These aren't necessarily related to the users set getting the empty value, but may be related to other oddities you see with these resource.

[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 have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.