Evaluation of module not needed when module is not deployed

[steini44as]

Terraform Version

Terraform v1.2.3
on windows_amd64
+ provider registry.terraform.io/hashicorp/azurerm v3.14.0

Terraform Configuration Files

resource "azurerm_virtual_network" "vnet" {
  name                = var.ResourceName
  resource_group_name = var.ResourceGroupName
  location            = var.Location
  address_space       = var.VNetAddressList
  dns_servers         = var.DnsServerIPAddressList == [""] ? null : var.DnsServerIPAddressList
}
module "virtual_network_hub"{
  count = local.var_config.VirtualNetworkHubObject == {} ? 0 : 1
  source = "./modules/virtual_network"
  ResourceName = local.var_config.VirtualNetworkHubObject.VirtualNetworkName
  ResourceGroupName = azurerm_resource_group.rg[local.var_config.ResourceGroupName].name
  Location = local.var_config.Location
  VirtualNetworkAddressList = local.var_config.VirtualNetworkHubObject.VirtualNetworkAddressList
  DnsServerIPAddressList = lookup(local.var_config.VirtualNetworkHubObject,"DnsServerIPAddressList", null) != null ? local.var_config.VirtualNetworkHubObject.DnsServerIPAddressList : null
}

Debug Output

none

Expected Behavior

If VirtualNetworkHubObject is empty, it shouldn't error/evaluate the ResourceName, ResourceGroupName etc).

Actual Behavior

Error: Unsupported attribute │ │ on main.tf line 54, in module "virtual_network_hub": │ 54: ResourceName = local.var_config.VirtualNetworkHubObject.VirtualNetworkName │ ├──────────────── │ │ local.var_config.VirtualNetworkHubObject is object with no attributes │ │ This object does not have an attribute named "VirtualNetworkName".

Now it tries to look for VirtualNetworkName inside the VirtualNetworkHubObject object.

Steps to Reproduce

1. 'terraform init'
2. 'terraform appy'

Additional Context

No response

References

No response

[jbardin]

Hi @steini44as,

Terraform decodes and validates the configuration as a whole before applying any of the specific configuration values. Since this is a known type violation, the validation process catches the error and reports it correctly. Because not all values can be known during validation, Terraform does not make any assumptions about how modules will be expanded, and all configuration is processed. The only way to fully remove a module from being evaluated is to remove it from the configuration.

Since Terraform is working as designed here, and this does not represent a bug in the CLI, I'm going to close this out. We use GitHub issues for tracking bugs and enhancements, rather than for questions. While we can sometimes help with certain simple problems here, it's better to use the community forum where there are more people ready to help.

Thanks!

[github-actions[bot]]

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