CODEWITHSUNDEEP
terraform
Dan Tracey
Dan Tracey

Reputation: 25

Using Terraform module output as input to local-exec provisioner

I'm trying to define a module testing framework for terraform and my approach is to use Pester, called from a local-exec provisioner in order to verify build is correct.

To this end I was hoping to be able to use output from the module, e.g:

output "windows_ip_address" {
  value = module.windowsservers.network_interface_private_ip
}

... as an input for a local-exec provisioner. e.g:

module "windowsservers" {
  source              = "../../"
  vm_hostname         = "host${random_id.ip_dns.hex}-windows" // line can be removed if only one VM module per resource group
  resource_group_name = azurerm_resource_group.test.name
  is_windows_image    = true
  admin_username      = var.admin_username
  admin_password      = var.admin_password
  vm_os_simple        = "WindowsServer"
  vnet_subnet_id      = azurerm_subnet.subnet1.id
}

resource "null_resource" "run-pestertest" {
  provisioner "local-exec" {
    #command     = "..\\test_azurerm_compute.ps1 -vmhostname test -vmip ${module.windowsservers.network_interface_private_ip}"
    command = "echo ${module.windowsservers.network_interface_private_ip}"
    interpreter  = ["pwsh", "-Command"]
  }
  depends_on = [module.windowsservers]
  triggers = {
    always_run = "${timestamp()}"
  }
}

...but i'm getting:

Error: Invalid template interpolation value: Cannot include the given value in a string template: string required.

I thought by using depends_on i'd be able to force terraform to graph it out in such a way that the "windowsserver" module would be inacted prior to null_resource - but I think maybe there is something fundamentally incorrect with what i'm doing!

Thanks Dan

Upvotes: 1

Views: 3201

Answers (1)

rv23
rv23

Reputation: 46

I apologize if this is a silly question, but have you verified the module output you want to use (module.windowsservers.network_interface_private_ip) is in fact typed as a string? Perhaps it's a list, or something else .. You can try "forcing" it to be a string in a locals block and see if that either fixes the error or changes it to indicate perhaps the output type isn't actually a string ..

locals = {
module_private_ip = "${tostring(module.windowsservers.network_interface_private_ip)}"
}

I only mention the locals block because it looks like you use it in multiple places, and using the locals means only one place it's used, and once place that could be spitting out the error about invalid type.

I've also used the locals block as a trick to deal with dependencies between modules as TF doesn't always seem to handle that well..

and I apologize for posting as an "answer", but I don't have the karma to post comments yet :)

Upvotes: 1

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