Question 105482 in Azure Question posted in
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Azure – Cannot assign variable from data.tf to variables.tf file

New to terraform, and have been building out the infrastructure recently.
I am trying to pull secrets from azure key vault and assign the keys to the variables.tf file depending on the environment(dev.tfvars, test.tfvars, etc). However when I execute the plan with the tfvar file as the parameter, I get an error with the following message:

Error: Variables not allowed

Here are the files and the relevant contents of it.

variables.tf:

variable "user_name" {
  type      = string
  sensitive = true
}

data.tf (referencing the azure key vault):

 data "azurerm_key_vault" "test" {
  name                = var.key_vault_name
  resource_group_name = var.resource_group
}

data "azurerm_key_vault_secret" "test" {
  name         = "my-key-vault-key-name"
  key_vault_id = data.azurerm_key_vault.test.id
}

test.tfvars:

user_name = "${data.azurerm_key_vault_secret.test.value}" # Where the error occurrs

Can anyone point out what I’m doing wrong here? And if so is there another way to achieve such a thing?

Tags:

2

Answers


  1. 0

    You can’t create dynamic variables. All variables must have known values before execution of your code. The only thing you could do is to use local, instead of variabile:

    locals {
  user_name = data.azurerm_key_vault_secret.test.value
}

    and then refer to it as local.user_name.

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  2. 0

    In Terraform a variable can be used for user input only. You can not assign to them anything dynamically computed from your code. They are like read-only arguments, for more info see Input Variables from the doc.

    If you want to assign a value to something for later use, you must use locals. For example:

    locals {
  user_name = data.azurerm_key_vault_secret.test.value
}

    Local values can be changed dynamically during execution. For more info, see Local Values.

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