Plan fails if KMS key is being created at the same time as the module

[brinnjoyce]

trafficstars

Describe the bug

If the KMS key is being created at the same time as the module, i.e. as a separate aws_kms_key resource or by setting enable_managed_kms_key the plan fails with this error:

╷
│ Error: Invalid count argument
│
│   on .terraform/modules/gitlab-runner/modules/terminate-agent-hook/iam.tf line 53, in data "aws_iam_policy_document" "kms_key":
│   53:   count = var.kms_key_id != "" ? 1 : 0
│
│ The "count" value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how many instances will be created. To work around this,
│ use the -target argument to first apply only the resources that the count depends on.

To Reproduce

Steps to reproduce the behavior: Try to use the module like this:

module "gitlab-runner" {
  source  = "cattle-ops/gitlab-runner/aws"
  version = "9.2.0"

  environment = "prod"
  runner_gitlab = {
    url                                           = var.gitlab_url
    preregistered_runner_token_ssm_parameter_name = var.token_ssm_parameter_name
  }

  enable_managed_kms_key = true

  subnet_id = var.subnet
  vpc_id    = var.vpc
}

Expected behavior

Terraform plan should not fail

Additional context

Caused by https://github.com/cattle-ops/terraform-aws-gitlab-runner/pull/1258