在Terraform中使用for_each时如何获取索引遍历嵌套对象

问题场景 #

现有如下Terraform本地变量定义，通过flatten处理得到sdlc_config后生成config_map：

locals {
    environments = {
        test-env = {
          configurations = [
            {
              account_id   = "123456789"
              account_name = "account-name-1"
              team         = "team-1"
              alias        = "us-east"
            },
            {
              account_id   = "123456789"
              account_name = "account-name-1"
              team         = "team-1"
              alias        = "us-west"
            },
            {
              account_id   = "987654321"
              account_name = "account-name-2"
              team         = "team-1"
              alias        = "us-east-account-2"
            },
            {
              account_id   = "987654321"
              account_name = "account-name-2"
              team         = "team-1"
              alias        = "us-west-account"
            }
          ]
        }
    }
}

locals {
    sdlc_config = flatten([
    for name, metadata in local.environments : [
      for config in metadata.configurations : {
        name         = name
        account_id   = config.account_id
        account_name = config.account_name
        team         = config.team
      }
    ]
])

config_map = {
   for each in distinct(local.sdlc_config) : "${each.name}" => { config_name = "${each.account_name}-${each.team}-${each.account_id}" }...
}

config_map的输出结构为：

{
   "test-env" = [
      {
         "config_name" = "account-name-1-team-1-123456789"
      },
      {
         "config_name" = "account-name-2-team-1-987654321"
      },
   ]
}

尝试在data块中用for_each遍历local.config_map时，因每个value是列表对象，无法直接通过索引引用config_name，当前写法不生效：

data "configuration" "configurations" {
   for_each = local.config_map
   name     = each.value[index].config_name
}

解决方案 #

方法一：重构config_map为扁平可遍历结构 #

直接调整config_map的生成逻辑，将每个配置项作为独立的map元素，使用唯一组合键作为key，这样for_each可以直接遍历每个配置项：

locals {
  config_map = {
    for item in distinct(local.sdlc_config) :
    "${item.name}:${item.account_name}-${item.team}-${item.account_id}" => {
      config_name = "${item.account_name}-${item.team}-${item.account_id}"
    }
  }
}

data "configuration" "configurations" {
  for_each = local.config_map
  name     = each.value.config_name
}

这种方式生成的config_map是扁平结构，每个key唯一标识一个配置项，for_each可以直接遍历每个元素，无需处理索引。

方法二：基于现有config_map生成扁平遍历集合 #

如果需要保留原config_map的结构，可以先将其扁平化，生成包含所有配置项的集合，再用于for_each：

locals {
  flattened_configs = flatten([
    for env_name, config_list in local.config_map : [
      for idx, config in config_list : {
        unique_key = "${env_name}-${idx}"
        config_name = config.config_name
      }
    ]
  ])

  # 转换为map用于for_each
  config_for_each = {
    for item in local.flattened_configs : item.unique_key => item
  }
}

data "configuration" "configurations" {
  for_each = local.config_for_each
  name     = each.value.config_name
}

这里通过flatten将config_map中每个列表的元素拆出，用env_name+索引生成唯一key，再转换为map后供for_each使用，确保每个遍历项唯一且可直接访问config_name。

内容的提问来源于stack exchange，提问作者Gary Toms