Terraform-为变量指定多个可能的值 [英] Terraform - Specifying multiple possible values for Variables

问题描述

CloudFormation提供了用于参数的AllowedValues，它指示该参数的可能值可以来自此列表。如何使用Terraform变量实现这一目标？列表的变量类型不提供此功能。因此，如果我希望变量仅具有两个可能的值，那么如何使用Terraform来实现这一点。我要复制的CloudFormation脚本是：

CloudFormation provides AllowedValues for Parameters which tells that the possible value of the parameter can be from this list. How can I achieve this with Terraform variables? The variable type of list does not provide this functionality. So, in case I want my variable to have value out of only two possible values, how can I achieve this with Terraform. CloudFormation script that I want to replicate is:

"ParameterName": {
        "Description": "desc",
        "Type": "String",
        "Default": true,
        "AllowedValues": [
            "true",
            "false"
        ]
   }

推荐答案

我不知道官方的方式，但是在Terraform问题中描述了一种有趣的技术：

I don't know of an official way, but there's an interesting technique described in a Terraform issue:

variable "values_list" {
  description = "acceptable values"
  type = "list"
  default = ["true", "false"]
}

variable "somevar" {
description = "must be true or false"
}

resource "null_resource" "is_variable_value_valid" {
  count = "${contains(var.values_list, var.somevar) == true ? 0 : 1}"
  "ERROR: The somevar value can only be: true or false" = true
}

更新：

现在，Terraform提供了实验性设置，可以启用自定义验证规则，尽管他们不建议在生产模块中使用它：

Terraform now offers an experimental setting to enable custom validation rules, though they don't recommend using this in production modules yet:

variable "somevar" {
  type = string
  description = "must be true or false"

  validation {
    condition     = can(regex("^(true|false)$", var.somevar))
    error_message = "Must be true or false."
  }
}

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