azure - Terraform:使用 If/Else 模式将资源属性分配给资源参数

Question

我正在使用IF/ELSE pattern在 Terraform 中构建具有或不具有公共(public) IP 的 NIC。分配 NIC 时会出现问题。我找不到一种技术可以让我选择用于创建 NIC 的资源(有或没有公共(public) IP)。使用三元运算失败，因为其中一项资源不存在。将资源放入列表中不会进行插值。如何分配正确的资源输出？

resource "azurerm_public_ip" "public_ip" {
    count                        = "${var.assign_public_ip}"
    name                         = "${format("${var.name}-pip%02d", count.index)}"
    location                     = "${var.location}"
    resource_group_name          = "${var.resource_group_name}"
    public_ip_address_allocation = "static"

    tags {
        environment = "${var.resource_group_name}"
    }
}

resource "azurerm_network_interface" "nic_with_public_ip" {
    count               = "${var.assign_public_ip}"
    name                = "${format("${var.name}-nic%02d", count.index)}"
    location            = "${var.location}"
    resource_group_name = "${var.resource_group_name}"

    ip_configuration {
        name                          = "ip_cfg"
        subnet_id                     = "${var.subnet_id}"
        private_ip_address_allocation = "dynamic"
        public_ip_address_id          = "${azurerm_public_ip.public_ip.id}"
    }
}

resource "azurerm_network_interface" "nic" {
    count               = "${1 - var.assign_public_ip}"
    name                = "${format("${var.name}-nic%02d", count.index)}"
    location            = "${var.location}"
    resource_group_name = "${var.resource_group_name}"

    ip_configuration {
        name                          = "ip_cfg"
        subnet_id                     = "${var.subnet_id}"
        private_ip_address_allocation = "dynamic"
    }
}

resource "azurerm_virtual_machine" "centos" {
    count                 = "${var.count}"
    name                  = "${format("${var.name}%02d", count.index)}"
    location              = "${var.location}"
    resource_group_name   = "${var.resource_group_name}"
    network_interface_ids = ["${var.assign_public_ip == 1 ? azurerm_network_interface.nic_with_public_ip.id : azurerm_network_interface.nic.id }"]
    vm_size               = "${var.size}"
    delete_os_disk_on_termination = true
    delete_data_disks_on_termination = true

    storage_image_reference {
        publisher = "OpenLogic"
        offer     = "CentOS"
        sku       = "7.3"
        version   = "latest"
    }

    storage_os_disk {
        name              = "${format("${var.name}-osdisk%02d", count.index)}"
        caching           = "ReadWrite"
        create_option     = "FromImage"
    }

    os_profile {
        computer_name  = "${format("${var.name}%02d", count.index)}"
        admin_username = "${var.admin_user}"
    }

    os_profile_linux_config {
        disable_password_authentication = true
        ssh_keys = {
            path = "/home/${var.admin_user}/.ssh/authorized_keys"
            key_data = "${var.ssh_key}"
    }
  }

  tags {
      environment = "${var.name}"
  }
}

此操作失败并出现以下错误: 运行计划时出错:发生 1 个错误:

* module.jumphost.azurerm_virtual_machine.centos: 1 error(s) occurred:

* module.jumphost.azurerm_virtual_machine.centos: Resource 'azurerm_network_interface.nic' not found for variable 'azurerm_network_interface.nic.id'

Answer 1

“splat 表达式”可用于获取从具有 count 的资源 block 创建的实例的属性值列表:

azurerm_network_interface.nic_with_public_ip.*.id

当 count = 0 时，这会返回一个空列表。在这种情况下，所有计数中始终只有 1，可以利用 concat 来选择存在的那个:

network_interface_ids = "${concat(azurerm_network_interface.nic_with_public_ip.*.id, azurerm_network_interface.nic.*.id)}"

由于network_interface_ids已经是一个列表，我们可以直接在这里分配concat的结果。由于在这些资源上分配 count 的方式，我们知道该列表始终只有一个元素，从而达到选择事件元素的预期结果。