config: allow local value interpolations in count

[apparentlymart]

There is some additional, early validation on the count meta-argument that verifies that only suitable variable types are used, and adding local values to this whitelist was missed in the initial implementation.

This fixes #15987.

[antgel]

@apparentlymart Thanks for this fix, I ran into the problem in as well. But I'm still suffering from the problem, using 0.10.4 which was released only a couple of days ago.

locals {
  availability_zones = [
    "${var.region}a", 
    "${var.region}b"
  ]
}

resource "aws_subnet" "sandbox-public" {
  count = "${length(locals.availability_zones)}"
  vpc_id = "${aws_vpc.sandbox.id}"
  cidr_block = "10.1.0.0/16"
  availability_zone = "${local.availability_zones[count.index]}"
  map_public_ip_on_launch = true

  tags {
    Name = "sandbox-public"
  }
}

Results in:

antony@tuxrocks:~/src/git/terraform$ terraform plan
Failed to load root config module: Error loading /home/antony/src/git/terraform/graduway.tf: locals.availability_zones: resource variables must be three parts: TYPE.NAME.ATTR in:

${length(locals.availability_zones)}

Did I miss something or is the bug still around?

[apparentlymart]

Hi @antgel,

I think the problem there is that you've written locals rather than local in that interpolation; Terraform thinks you're asking for a resource of type "locals" since that's the default behavior for prefixes that aren't recognized.

I think if you change it to local then it will work:

  count = "${length(local.availability_zones)}"

[antgel]

Oops, thanks for the pointer. :)

[ghost]

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