定义输入变量

4 分钟
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Terraform

你现在已经掌握了足够的 Terraform 知识来创建有用的配置，但到目前为止的示例都使用了硬编码值。Terraform 配置可以包含变量，使你的配置更具动态性和灵活性。

注意

本教程基于之前的教程中的配置。如果你尚未完成，请立即完成。

定义你的变量

在你的 learn-terraform-azure 目录下，创建一个名为 variables.tf 的新文件。复制并粘贴以下变量声明。

variables.tf

variable "resource_group_name" {
  default = "myTFResourceGroup"
}

此声明包括变量的默认值，因此 resource_group_name 变量将不会是必需的输入。

使用你的变量更新你的 Terraform 配置

更新你的 azurerm_resource_group 配置，以使用输入变量来表示资源组名称。修改虚拟机块如下

main.tf

resource "azurerm_resource_group" "rg" {
  name     = var.resource_group_name
  location = "westus2"

  tags = {
    Environment = "Terraform Getting Started"
    Team        = "DevOps"
  }
}

应用你的配置

重新运行 terraform apply 以使用输入变量重新创建你的基础设施。回复 yes 以确认操作。

$ terraform apply

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:
##...
Plan: 2 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

azurerm_resource_group.rg: Creating...
azurerm_resource_group.rg: Creation complete after 1s [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup]
azurerm_virtual_network.vnet: Creating...
azurerm_virtual_network.vnet: Creation complete after 7s [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup/providers/Microsoft.Network/virtualNetworks/myTFVnet]

Apply complete! Resources: 2 added, 0 changed, 0 destroyed.

现在再次应用配置，这次通过使用 -var 标志传递变量来覆盖默认资源组名称。更新资源组名称是一项破坏性更新，它会强制 Terraform 重创建资源，进而重创建依赖于它的虚拟网络。在确认提示中输入 yes 来重命名资源组并创建新资源。

$ terraform apply -var "resource_group_name=myNewResourceGroupName"
azurerm_resource_group.rg: Refreshing state... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup]
azurerm_virtual_network.vnet: Refreshing state... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup/providers/Microsoft.Network/virtualNetworks/myTFVnet]

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
-/+ destroy and then create replacement

Terraform will perform the following actions:

  # azurerm_resource_group.rg must be replaced
-/+ resource "azurerm_resource_group" "rg" {
      ~ id       = "/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup" -> (known after apply)
      ~ name     = "myTFResourceGroup" -> "myNewResourceGroupName" # forces replacement
        tags     = {
            "Environment" = "Terraform Getting Started"
            "Team"        = "DevOps"
        }
        # (1 unchanged attribute hidden)
    }

  # azurerm_virtual_network.vnet must be replaced
-/+ resource "azurerm_virtual_network" "vnet" {
      - dns_servers           = [] -> null
      ~ guid                  = "260a1a64-08ed-4693-84d8-eda800326faa" -> (known after apply)
      ~ id                    = "/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup/providers/Microsoft.Network/virtualNetworks/myTFVnet" -> (known after apply)
        name                  = "myTFVnet"
      ~ resource_group_name   = "myTFResourceGroup" -> "myNewResourceGroupName" # forces replacement
      ~ subnet                = [] -> (known after apply)
      - tags                  = {} -> null
        # (3 unchanged attributes hidden)
    }

Plan: 2 to add, 0 to change, 2 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

azurerm_virtual_network.vnet: Destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup/providers/Microsoft.Network/virtualNetworks/myTFVnet]
azurerm_virtual_network.vnet: Still destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-...osoft.Network/virtualNetworks/myTFVnet, 10s elapsed]
azurerm_virtual_network.vnet: Destruction complete after 11s
azurerm_resource_group.rg: Destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myTFResourceGroup]
azurerm_resource_group.rg: Still destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-...dfb29/resourceGroups/myTFResourceGroup, 10s elapsed]
azurerm_resource_group.rg: Still destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-...dfb29/resourceGroups/myTFResourceGroup, 20s elapsed]
azurerm_resource_group.rg: Still destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-...dfb29/resourceGroups/myTFResourceGroup, 30s elapsed]
azurerm_resource_group.rg: Still destroying... [id=/subscriptions/c9ed8610-47a3-4107-a2b2-...dfb29/resourceGroups/myTFResourceGroup, 40s elapsed]
azurerm_resource_group.rg: Destruction complete after 48s
azurerm_resource_group.rg: Creating...
azurerm_resource_group.rg: Creation complete after 1s [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myNewResourceGroupName]
azurerm_virtual_network.vnet: Creating...
azurerm_virtual_network.vnet: Creation complete after 6s [id=/subscriptions/c9ed8610-47a3-4107-a2b2-a322114dfb29/resourceGroups/myNewResourceGroupName/providers/Microsoft.Network/virtualNetworks/myTFVnet]

Apply complete! Resources: 2 added, 0 changed, 2 destroyed.

通过命令行设置变量不会保存它们的值。Terraform 支持多种使用和设置变量的方式，以便您避免在执行命令时反复输入它们。要了解更多信息，请遵循我们的深入教程，使用变量自定义 Terraform 配置。

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