Terraform: quoted or unquoted resource references?

Question

I am new to terraform using vs code and the "Terraform" extension from Mikael Olenfalk.

I learned using string interpolation where I can ctrl+space (intellisense) and use resource references. However I am unsure if this is always required (to reference resources in my *.tf file)? If I dont need to interpolate but only reference a resource, using the "string-interpolation-way" is really noisy.

Lets say I have a azurerm_storage_account resource of the name static-site. I can do the following and vs code says all is okay.

name = "${azurerm_storage_account.static-site.name}"

or I can do this

name = azurerm_storage_account.static-site.name

and I am getting an error unexpected token while parsing list: IDENT

By contrast if I look around on the official docs site, there is clearly some cases where quotes are not used, e.g. see the example in this section https://www.terraform.io/docs/configuration/resources.html#depends_on-explicit-resource-dependencies

resource "aws_iam_role_policy" "example" {
  name   = "example"
  role   = aws_iam_role.example.name
  policy = jsonencode({
    "Statement" = [{
      # This policy allows software running on the EC2 instance to
      # access the S3 API.
      "Action" = "s3:*",
      "Effect" = "Allow",
    }],
  })
}

resource "aws_instance" "example" {
  ami           = "ami-a1b2c3d4"
  instance_type = "t2.micro"

  iam_instance_profile = aws_iam_instance_profile.example <--------------- !!!

  # However, if software running in this EC2 instance needs access
  # to the S3 API in order to boot properly, there is also a "hidden"
  # dependency on the aws_iam_role_policy that Terraform cannot
  # automatically infer, so it must be declared explicitly:
  depends_on = [
    aws_iam_role_policy.example,
  ]
}

Which would give errors for me. Or is this especially required for azure resources (which I use)? The example above was with aws.

Cheers

VSCode is still not HCL2/Terraform 0.12 compatible last time I checked. Atom is (TF 0.12; unsure HCL2) because I wrote it, but no reason to switch because I am sure it will come to VScode eventually. — Matt Schuchard
I found the section in the docs clearly stating this is a tf 0.12 feature: terraform.io/upgrade-guides/0-12.html#first-class-expressions — baouss
@baouss the plugin does not support terraform 12, the issue with not the terraform, its wtih plugin — Adiii
And here is the exact Github issue for this github.com/mauve/vscode-terraform/issues/180 — baouss

Adiii Adiii · Accepted Answer · 2019-07-25T15:32:19

I believe the issue with JSON encode Function, not with interpolation syantx. To overcome this error you can heredoc syantx. A multi-line string value can be provided using heredoc syntax.

resource "aws_iam_role_policy" "example" {
  name   = "example"
  role   = "${aws_iam_role.example.name}"
  policy = <<EOF
  {
    "Version": "2012-10-17",
    "Statement" = [
          {
            "Sid": "VisualEditor5",
            "Effect": "Allow",
            "Action": "s3:*",
            "Resource": "*"
         }
    ]
  }
  EOF
}

To verify the issue just comment out role = "${aws_iam_role.example.name}".

While the issue disappears using heredoc syntax.

The reason behind this error is that "Terraform 0.12 support is still not available" by the plugin provider.

Terraform: quoted or unquoted resource references?

1 Answers