Terraform 0.12：无需枚举属性批量增改Map中的对象

问题背景 #

现有如下结构的Map变量：

stuff = {
  object-1 = {
    id                    = "1"
    main_value            = "blue"
    additional_in_values  = ["red"]
    additional_out_values = ["green"]
    more_values           = "foo"
  },
  object-2 = {
    id                    = "2"
    main_value            = "green"
    additional_in_values  = ["blue"]
    additional_out_values = ["red"]
    more_values           = "fee"
  },
  object-3 = {
    id                    = "3"
    main_value            = "red"
    additional_in_values  = ["green"]
    additional_out_values = ["blue"]
    more_values           = "fie"
  }
}

需要实现：

• 遍历Map中的每个对象，无需硬编码所有原有属性
• 新增inbound_all（由main_value与additional_in_values拼接）、outbound_all（由main_value与additional_out_values拼接）属性
• 保留对象所有原有属性
• 支持后续灵活新增、删除或修改属性的场景

现有方案的问题：

• local.unmaintainable：硬枚举所有属性，对象属性动态变化时需同步修改，可维护性极差
• local.transformed-stuff：仅生成新增属性，完全丢失原有对象数据

现有代码 #

variable "stuff" {
  type = map(object({
    id                    = string
    main_value            = string
    additional_in_values  = list(string)
    additional_out_values = list(string)
    more_values           = string
  }))
}

locals {
  unmaintainable = {
    for stuff_key, stuff_details in var.stuff :
      stuff_key => {
        id = stuff_details.id
        main_value = stuff_details.main_value
        additional_out_values = stuff_details.additional_out_values
        additional_in_values = stuff_details.additional_in_values
        more_values = stuff_details.more_values
        inbound_all     = concat([stuff_details.main_value], stuff_details.additional_in_values)
        outbound_all    = concat([stuff_details.main_value], stuff_details.additional_out_values)
      }
   }

  transformed-stuff = {
    for stuff_key, stuff_details in var.stuff :
    stuff_key => {
      inbound_all     = concat([stuff_details.main_value], stuff_details.additional_in_values)
      outbound_all    = concat([stuff_details.main_value], stuff_details.additional_out_values)
    }
  }
}

output "stuff" {
  value = var.stuff
}

output "unmaintainable" {
    value = local.unmaintainable
}

output "transformed-stuff" {
  value = local.transformed-stuff
}

当前输出 #

Outputs:

stuff = {
  "object-1" = {
    "additional_in_values" = [
      "red",
    ]
    "additional_out_values" = [
      "green",
    ]
    "id" = "1"
    "main_value" = "blue"
    "more_values" = "foo"
  }
  "object-2" = {
    "additional_in_values" = [
      "blue",
    ]
    "additional_out_values" = [
      "red",
    ]
    "id" = "2"
    "main_value" = "green"
    "more_values" = "foo"
  }
  "object-3" = {
    "additional_in_values" = [
      "green",
    ]
    "additional_out_values" = [
      "blue",
    ]
    "id" = "3"
    "main_value" = "red"
    "more_values" = "foo"
  }
}
transformed-stuff = {
  "object-1" = {
    "inbound_all" = [
      "blue",
      "red",
    ]
    "outbound_all" = [
      "blue",
      "green",
    ]
  }
  "object-2" = {
    "inbound_all" = [
      "green",
      "blue",
    ]
    "outbound_all" = [
      "green",
      "red",
    ]
  }
  "object-3" = {
    "inbound_all" = [
      "red",
      "green",
    ]
    "outbound_all" = [
      "red",
      "blue",
    ]
  }
}
unmaintainable = {
  "object-1" = {
    "additional_in_values" = [
      "red",
    ]
    "additional_out_values" = [
      "green",
    ]
    "id" = "1"
    "inbound_all" = [
      "blue",
      "red",
    ]
    "main_value" = "blue"
    "more_values" = "foo"
    "outbound_all" = [
      "blue",
      "green",
    ]
  }
  "object-2" = {
    "additional_in_values" = [
      "blue",
    ]
    "additional_out_values" = [
      "red",
    ]
    "id" = "2"
    "inbound_all" = [
      "green",
      "blue",
    ]
    "main_value" = "green"
    "more_values" = "foo"
    "outbound_all" = [
      "green",
      "red",
    ]
  }
  "object-3" = {
    "additional_in_values" = [
      "green",
    ]
    "additional_out_values" = [
      "blue",
    ]
    "id" = "3"
    "inbound_all" = [
      "red",
      "green",
    ]
    "main_value" = "red"
    "more_values" = "fee"
    "outbound_all" = [
      "red",
      "blue",
    ]
  }
}

可维护性解决方案 #

利用Terraform的merge函数或对象展开语法，实现动态合并原有属性与新增属性，无需硬编码原有字段：

基础实现（新增属性+保留原有） #

locals {
  maintainable_transform = {
    for k, v in var.stuff : k => merge(v, {
      inbound_all  = concat([v.main_value], v.additional_in_values)
      outbound_all = concat([v.main_value], v.additional_out_values)
    })
  }
}

output "maintainable_transform" {
  value = local.maintainable_transform
}

扩展场景：删除指定属性 #

如果需要删除某个原有属性（比如more_values），可以通过属性过滤+合并实现：

locals {
  maintainable_transform_with_remove = {
    for k, v in var.stuff : k => merge(
      # 过滤掉不需要的属性
      { for attr, val in v : attr => val if attr != "more_values" },
      {
        inbound_all  = concat([v.main_value], v.additional_in_values)
        outbound_all = concat([v.main_value], v.additional_out_values)
      }
    )
  }
}

output "maintainable_transform_with_remove" {
  value = local.maintainable_transform_with_remove
}

扩展场景：修改原有属性值 #

如果需要修改原有属性（比如把main_value转为大写），直接在merge里重定义该属性即可覆盖原有值：

locals {
  maintainable_transform_with_modify = {
    for k, v in var.stuff : k => merge(v, {
      main_value   = upper(v.main_value)
      inbound_all  = concat([upper(v.main_value)], v.additional_in_values)
      outbound_all = concat([upper(v.main_value)], v.additional_out_values)
    })
  }
}

output "maintainable_transform_with_modify" {
  value = local.maintainable_transform_with_modify
}

输出示例（基础实现） #

maintainable_transform = {
  "object-1" = {
    "additional_in_values" = [
      "red",
    ]
    "additional_out_values" = [
      "green",
    ]
    "id" = "1"
    "inbound_all" = [
      "blue",
      "red",
    ]
    "main_value" = "blue"
    "more_values" = "foo"
    "outbound_all" = [
      "blue",
      "green",
    ]
  }
  "object-2" = {
    "additional_in_values" = [
      "blue",
    ]
    "additional_out_values" = [
      "red",
    ]
    "id" = "2"
    "inbound_all" = [
      "green",
      "blue",
    ]
    "main_value" = "green"
    "more_values" = "fee"
    "outbound_all" = [
      "green",
      "red",
    ]
  }
  "object-3" = {
    "additional_in_values" = [
      "green",
    ]
    "additional_out_values" = [
      "blue",
    ]
    "id" = "3"
    "inbound_all" = [
      "red",
      "green",
    ]
    "main_value" = "red"
    "more_values" = "fie"
    "outbound_all" = [
      "red",
      "blue",
    ]
  }
}

内容的提问来源于stack exchange，提问作者rpc