Terraform使用for_each遍历列表创建Servicebus主题报错如何解决

报错的核心原因是Terraform的for_each仅支持map类型或字符串set类型作为入参，你当前定义的local.topics是复杂object结构组成的tuple（列表），无法通过toset()转换为符合要求的入参类型。

你只需要调整local块的输出结构，把原来的列表转换为以主题名称为唯一key的map即可，修改后的配置如下：

调整后的local块代码 #

locals {
  topics = {
    for topic in var.topics : topic.name => merge({
      name                       = ""
      status                     = "Active"
      auto_delete_on_idle        = null
      default_message_ttl        = null
      enable_batched_operations  = null
      enable_express             = null
      enable_partitioning        = null
      max_size                   = null
      enable_duplicate_detection = null
      enable_ordering            = null
      authorization_rules        = []
      subscriptions              = []
      duplicate_detection_history_time_window = null
    }, topic)
  }
}

调整后的maintf资源块代码 #

resource "azurerm_servicebus_topic" "topic" {
  for_each = local.topics

  name                = each.value.name
  resource_group_name = var.resource_group_name
  namespace_name      = azurerm_servicebus_namespace.servicebus.name

  status                       = each.value.status
  auto_delete_on_idle          = each.value.auto_delete_on_idle
  default_message_ttl          = each.value.default_message_ttl
  enable_batched_operations    = each.value.enable_batched_operations
  enable_express               = each.value.enable_express
  enable_partitioning          = each.value.enable_partitioning
  max_size_in_megabytes        = each.value.max_size
  requires_duplicate_detection = each.value.enable_duplicate_detection
  support_ordering             = each.value.enable_ordering

  duplicate_detection_history_time_window = each.value.duplicate_detection_history_time_window
}

这种写法以主题名称作为map的唯一key，既符合for_each的参数要求，后续调整主题配置时，Terraform也能根据key精准识别需要变更的资源，不会因为列表顺序变化触发不必要的重建。如果存在主题名称重复的场景，也可以把map的key替换为索引idx，写法为for idx, topic in var.topics : tostring(idx) => merge(xxx, topic)即可。

内容的提问来源于stack exchange，提问作者prakashrajansakthivel