Terraform内联虚拟网络中子网ID获取与路由表关联求助

我正在使用Terraform创建虚拟网络，子网是在虚拟网络资源块内创建（而非使用独立的资源块）。我尝试为这些子网关联一些路由表，但不确定如何获取在虚拟网络内创建的子网的资源ID，能否有人提供帮助？

main.tf

terraform {
  required_providers {
    azurerm = {
      source = "hashicorp/azurerm"
      version = "3.24.0"
    }
  }
}

provider "azurerm" {
    skip_provider_registration = true
    features {}
}

###########################
# RESOURCE GROUP CREATION #
###########################
resource "azurerm_resource_group" "rg" {
    name = var.rg.name
    location = var.rg.location
}

############################
# VIRTUAL NETWORK CREATION #
############################
resource "azurerm_virtual_network" "vnet" {
    name = var.vnet.name
    resource_group_name = azurerm_resource_group.rg.name
    location = azurerm_resource_group.rg.location
    address_space = var.vnet.address_space
    dns_servers = var.vnet.dns_servers

    subnet {
        name = var.vnet.subnet1_name
        address_prefix = var.vnet.subnet1_address_prefix
    }

    subnet {
        name = var.vnet.subnet2_name
        address_prefix = var.vnet.subnet2_address_prefix
    }

    subnet {
        name = var.vnet.subnet3_name
        address_prefix = var.vnet.subnet3_address_prefix
    }

    subnet {
        name = var.vnet.subnet4_name
        address_prefix = var.vnet.subnet4_address_prefix
    }

    subnet {
        name = var.vnet.subnet5_name
        address_prefix = var.vnet.subnet5_address_prefix
    }
}

########################
# ROUTE TABLE CREATION #
########################
resource "azurerm_route_table" "fslogix_rt" {
  name = var.rt.fslogix.name
  resource_group_name = azurerm_resource_group.rg.name
  location = azurerm_resource_group.rg.location
  disable_bgp_route_propagation = false
}

resource "azurerm_route_table" "back_office_rt" {
  name = var.rt.back_office.name
  resource_group_name = azurerm_resource_group.rg.name
  location = azurerm_resource_group.rg.location
  disable_bgp_route_propagation = false
}

resource "azurerm_route_table" "dev_dev_rt" {
  name = var.rt.dev_dev.name
  resource_group_name = azurerm_resource_group.rg.name
  location = azurerm_resource_group.rg.location
  disable_bgp_route_propagation = false
}

resource "azurerm_route_table" "dev_prod_rt" {
  name = var.rt.dev_prod.name
  resource_group_name = azurerm_resource_group.rg.name
  location = azurerm_resource_group.rg.location
  disable_bgp_route_propagation = false
}

resource "azurerm_route_table" "front_office_rt" {
  name = var.rt.front_office.name
  resource_group_name = azurerm_resource_group.rg.name
  location = azurerm_resource_group.rg.location
  disable_bgp_route_propagation = false
}

##################
# ROUTE CREATION #
##################
resource "azurerm_route" "fslogix_routes" {
  for_each = var.fslogix_routes
  name = each.value.name
  resource_group_name = azurerm_resource_group.rg.name
  route_table_name = azurerm_route_table.fslogix_rt.name
  address_prefix = each.value.address_prefix
  next_hop_type = each.value.next_hop_type
  next_hop_in_ip_address = each.value.next_hop_in_ip_address
}

resource "azurerm_route" "back_office_routes" {
  for_each = var.back_office_routes
  name = each.value.name
  resource_group_name = azurerm_resource_group.rg.name
  route_table_name = azurerm_route_table.back_office_rt.name
  address_prefix = each.value.address_prefix
  next_hop_type = each.value.next_hop_type
  next_hop_in_ip_address = each.value.next_hop_in_ip_address
}

resource "azurerm_route" "dev_dev_routes" {
  for_each = var.developer_dev_routes
  name = each.value.name
  resource_group_name = azurerm_resource_group.rg.name
  route_table_name = azurerm_route_table.dev_dev_rt.name
  address_prefix = each.value.address_prefix
  next_hop_type = each.value.next_hop_type
  next_hop_in_ip_address = each.value.next_hop_in_ip_address
}

resource "azurerm_route" "dev_prod_routes" {
  for_each = var.developer_prod_routes
  name = each.value.name
  resource_group_name = azurerm_resource_group.rg.name
  route_table_name = azurerm_route_table.dev_prod_rt.name
  address_prefix = each.value.address_prefix
  next_hop_type = each.value.next_hop_type
  next_hop_in_ip_address = each.value.next_hop_in_ip_address
}

resource "azurerm_route" "front_office_routes" {
  for_each = var.front_office_routes
  name = each.value.name
  resource_group_name = azurerm_resource_group.rg.name
  route_table_name = azurerm_route_table.front_office_rt.name
  address_prefix = each.value.address_prefix
  next_hop_type = each.value.next_hop_type
  next_hop_in_ip_address = each.value.next_hop_in_ip_address
}

###########################
# ROUTE TABLE ASSOICATION #
###########################
resource "azurerm_subnet_route_table_association" "fslogix_rta" {
  subnet_id = ???????????????????????????????????????
  route_table_id = azurerm_route_table.fslogix_rt.id
}

当在azurerm_virtual_network资源块内定义子网时，Terraform会自动将这些子网暴露为subnets列表属性，每个元素包含id、name等核心字段，你可以通过以下方式获取子网ID并关联路由表：

1. 单个子网的路由表关联 #

使用for表达式筛选目标子网，再通过one()函数取出唯一匹配的子网ID（确保子网名称唯一）：

resource "azurerm_subnet_route_table_association" "fslogix_rta" {
  subnet_id      = one([for s in azurerm_virtual_network.vnet.subnets : s.id if s.name == var.vnet.subnet1_name])
  route_table_id = azurerm_route_table.fslogix_rt.id
}

2. 批量关联所有子网（推荐） #

如果每个子网都对应一个路由表，可通过定义映射关系+for_each批量创建关联资源，减少重复代码：

# 定义子网名称与对应路由表ID的映射
locals {
  subnet_rt_mapping = {
    var.vnet.subnet1_name = azurerm_route_table.fslogix_rt.id
    var.vnet.subnet2_name = azurerm_route_table.back_office_rt.id
    var.vnet.subnet3_name = azurerm_route_table.dev_dev_rt.id
    var.vnet.subnet4_name = azurerm_route_table.dev_prod_rt.id
    var.vnet.subnet5_name = azurerm_route_table.front_office_rt.id
  }
}

# 批量生成路由表关联资源
resource "azurerm_subnet_route_table_association" "all" {
  for_each = local.subnet_rt_mapping

  subnet_id      = one([for s in azurerm_virtual_network.vnet.subnets : s.id if s.name == each.key])
  route_table_id = each.value
}

注意事项 #

• 确保变量中定义的子网名称与虚拟网络内的子网名称完全匹配，否则会出现找不到子网的错误
• 若使用Terraform 0.13以下版本，可替换one()为element([...], 0)，但建议升级到新版本以获得更安全的语法支持

内容的提问来源于stack exchange，提问作者Jon