config attribute not expected in terraform_remote_state data source

[pawwe]

Extension Version

v2.28.2

VS Code Version

Version: 1.83.1
Commit: f1b07bd25dfad64b0167beb15359ae573aecd2cc
Date: 2023-10-10T23:45:31.402Z
Electron: 25.8.4
ElectronBuildId: 24154031
Chromium: 114.0.5735.289
Node.js: 18.15.0
V8: 11.4.183.29-electron.0
OS: Linux x64 6.5.7-200.fc38.x86_64

Operating System

Linux fws 6.5.7-200.fc38.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Oct 11 04:07:58 UTC 2023 x86_64 GNU/Linux

Terraform Version

Terraform v1.6.2 on linux_amd64

Steps to Reproduce

Create a terraform_remote_state data source with a config argument where the backend argument is a variable.

Expected Behavior

Should not throw "Unexpected attribute" error.

Actual Behavior

Unexpected attribute: An attribute named "config" is not expected here

Terraform Configuration

variable "terraform_rs" {
  default = {
    backend              = "azurerm"
    workspace            = "***"
    storage_account_name = "***"
    container_name       = "***"
    key                  = "***"
    access_key           = "***"
  }
}

data "terraform_remote_state" "this" {
  backend   = var.terraform_rs.backend
  workspace = var.terraform_rs.workspace
  config = {
    storage_account_name = var.terraform_rs.storage_account_name
    container_name       = var.terraform_rs.container_name
    key                  = var.terraform_rs.key
    access_key           = var.terraform_rs.access_key
  }
}

Project Structure

No response

Gist

No response

Anything Else?

No response

Workarounds

Downgrading to v2.27.2 or "hard coding" the backend attribute to "azurerm" resolves this problem.

References

• terraform_remote_state config incorrectly flagged with errors #1580

Help Wanted

• I'm interested in contributing a fix myself

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[radeksimko]

I was able to reproduce the bug, thank you for attaching the configuration @pawwe

It indeed looks like that we don't account for the possibility of backend being dynamically provided inside of terraform_remote_state data source. 🤔

[radeksimko]

Notes for whoever gets to work on the fix:

I think we may need to update the logic in https://github.com/hashicorp/hcl-lang/blob/cc41e378f3a4c832a8e8e1fdde1c3705ee66e20c/decoder/internal/schemahelper/block_schema.go#L95-L98 to ensure that in this context dependent body lookup is treated as unsuccessful (unless it is already?) and that should in turn make sure that the validator receives the appropriate context, as per https://github.com/hashicorp/hcl-lang/blob/cc41e378f3a4c832a8e8e1fdde1c3705ee66e20c/decoder/internal/walker/walker.go#L91-L94 and unknown attributes won't be flagged up.

On a separate note we could create a follow-up issue to enable validation in such a dynamic context but I expect that will be a bit more involved.

[radeksimko]

This was addressed in hashicorp/hcl-lang#339 and will be part of the next release.

[github-actions]

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