templatefile doesn't wait for dependency described in resource block

[d-helios]

Terraform Version

Terraform v0.12.26
+ provider.local v1.4.0

Terraform Configuration Files

main.tf

variable "templates" {
  type = list(object({
    name = string
    value = string
  }))
}

resource "local_file" "origin" {
  count = length(var.templates)
  filename = "${path.module}/${var.templates[count.index].name}.json"
  content = var.templates[count.index].value
}

resource "local_file" "rendered" {
  count = length(var.templates)
  filename = "${path.module}/${var.templates[count.index].name}.rendered.json"
  content = templatefile(local_file.origin[count.index].filename, {tf_version = "v0.12.26"})
  depends_on = [
    local_file.origin
  ]
}

input.tfvars

templates = [
  {
    name = "my_template_1"
    value = "tf_version = $${tf_version}"
  },
  {
    name = "my_template_2"
    value = "tf_version = $${tf_version}"
  }
]

Expected Behavior

1. resource local_file.origin create a couple of files that are used as input for resource local_file.rendered

Actual Behavior

1. terraform ignore depends_on block which leads to the following error.
   Call to function "templatefile" failed: no file exists at my_template_1.json

Steps to Reproduce

1. terraform init
2. terraform apply -auto-approve -var-file=input.tfvars

[danieldreier]

Hello! I appreciate you reporting this, and I'm sorry this behavior isn't more obvious.

I think that what you're running into here is that functions always run at the very beginning of a terraform run, before any resources are created at all. I totally understand what you're trying to do here, but it won't work like this because files referenced by Terraform functions must exist before the terraform run starts.

I'm going to close this because I created a meta-issue tracking this broader category of issue - I probably triage about an issue a day relate to this, and it's time to start gathering data for a refactor, better documentation, better error messages, something to make this behavior more obvious.

If you want more guidance on how to work around this, your best bet is to seek support on the community forum.

[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.