How to pass Outputs from One Module to another?

Question

I have two modules.

one is called module-azure-vnet
second is called module-azure-vm-instance-zabbix-proxy

I want to pass Outputs from module module-azure-vnet to module module-azure-vm-instance-zabbix-proxy. First module is working properly, but second needs inputs for subnet, security group and route.

main.tf

module "module-azure-vnet-dtap" {
  source = "/Users/username/project/module-azure-vnet-dtap"
}

variable "subnets_id_wan" {}

module "module-azure-vm-instance-zabbix-proxy" {
  source = "/Users/username/project/module-azure-vm-instance-zabbix-proxy"
  azurerm_subnet = "${module.module-azure-vnet-dtap.azurerm_subnet.wan.id}"
}

Error: resource 'azurerm_network_interface.no_public_ip' config: unknown resource 'azurerm_subnet.wan' referenced in variable azurerm_subnet.wan.id

Error: resource 'azurerm_network_security_rule.security_rule_default' config: unknown resource 'azurerm_network_security_group.wan' referenced in variable azurerm_network_security_group.wan.name

Error: module "module-azure-vm-instance-zabbix-proxy": "azurerm_subnet" is not a valid argument

In module module-azure-vnet-dtap

resource "azurerm_subnet" "wan" {
  count                     = "${var.enable_wan_subnet ? 1 : 0}"
  provider                  = "azurerm.base"
  name                      = "${format("%s-%s-%s", var.environment_name, "WAN", "Subnet")}"
  virtual_network_name      = "${azurerm_virtual_network.this.name}"
  resource_group_name       = "${azurerm_resource_group.this.name}"
  address_prefix            = "${cidrsubnet(var.cidr_block,5,count.index)}"
  route_table_id            = "${azurerm_route_table.wan.id}"
  network_security_group_id = "${azurerm_network_security_group.wan.id}"
}

resource "azurerm_network_security_group" "wan" {
  count               = "${var.enable_wan_subnet ? 1 : 0}"
  provider            = "azurerm.base"
  name                = "${format("%s-%s", var.environment_name, "WAN-Subnet-Security-Group")}"
  location            = "${azurerm_resource_group.this.location}"
  resource_group_name = "${azurerm_resource_group.this.name}"
}

output "subnets_id_wan" {
  value = "${azurerm_subnet.wan.*.id}"

  depends_on = [
    "azurerm_subnet.wan",
  ]
}

Try commenting out the module "module-azure-vm-instance-zabbix-proxy" block and then run terraform init && terraform refresh && terraform show | less and look at all the output names and values to see if the module is outputting the correct value or if you're passing in the correct output to the zabbix proxy module. — SomeGuyOnAComputer
– SomeGuyOnAComputer, Commented Jan 20, 2019 at 16:13

Dejan Bodiroga · Accepted Answer · 2019-01-25 12:01:23Z

I've found solution myself, here is the whole structure what is needed in order to connect two modules.

set variables in VNET module example:

variable "resource_group_name" {
      default     = "default_resource_group"
      }

      variable "region_name" {
      default     = "ukwest"
      }

declare outputs:

output "security_groups_id_wan" {
      value = "${element(concat(azurerm_network_security_group.wan.*.id, list("")),0)}"

        depends_on = [
          "azurerm_subnet.wan",
          ]
      }

you need variables in zabbix proxy module to receive values>

variable "resource_group_name" {
        default = ""
        }
        variable "resource_group_location" {
        default = ""
        }

and in external folder where is the main.tf for modules>

module "module-azure-vm-instance-zabbix-proxy" {
        source = "/Users/username/project/module-azure-vm-instance-zabbix-proxy"
        resource_group_name = "${module.module-azure-vnet-dtap.resource_group_name}"
        resource_group_location = "${module.module-azure-vnet-dtap.resource_group_location}"
        subnets_id_wan = "${module.module-azure-vnet-dtap.subnets_id_wan}"
        security_groups_name = "${module.module-azure-vnet-dtap.security_groups_name_dmz}"
        environment_name = "${module.module-azure-vnet-dtap.environment_name}"
      }

      module module-azure-vnet-dtap {
        source = "/Users/username/project/module-azure-vnet-dtap"
      }

4c74356b41 · Accepted Answer · 2019-01-20 14:53:02Z

2

you should reference output like this:

"${module.MODULE_NAME.OUTPUT_NAME}"

in your case it should be:

"${module.module-azure-vnet-dtap.subnets_id_wan}"

also, you can only access outputs, not resources from the module (afaik).

answered Jan 20, 2019 at 14:53

4c74356b41

71.4k7 gold badges118 silver badges155 bronze badges

1 Comment

Dejan Bodiroga Over a year ago

Hi, Got same errors after changing azurerm_subnet.wan.id to subnets_id_wan

Collectives™ on Stack Overflow

How to pass Outputs from One Module to another?

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related