Terraform用for_each部署多ECS服务时遇ALB属性错误求助

错误信息 #

│ Error: Unsupported attribute
│ 
│   on main.tf line 42, in module "ecs":
│   42:   alb_target_groups = module.alb.alb_target_groups
│    ├────────────────
│     │ module.alb is a object
│ 
│ This object does not have an attribute named "alb_target_groups".

相关配置代码 #

main.tf #

module "alb" {
  source             = "./modules/alb"
  vpc_id             = module.network.vpc_id
  security_group_alb = module.security.security_group_alb
  public_subnets     = module.network.public_subnets
  customer_env       = local.customer_env
  env                = var.env
  alb_target_groups  = local.alb_target_groups
  listeners          = var.alb_config.listeners
}
module "ecs" {
  source           = "./modules/ecs"
  family_name      = var.family_name
  env              = var.env
  ecs_service_name = var.ecs_service_name
  service_config     = var.customer_config
  alb_target_groups  = module.alb.alb_target_groups
  # alb_target_groups      = local.alb_target_groups
}

env.tfvars #

ecs_service_name = ["customer"]

alb_config = {
  name = "Public-Alb"
  listeners = {
    "HTTP" = {
      listener_port     = 80
      listener_protocol = "HTTP"

    }
  }
}
customer_config = {
  "customer" = {
    name          = "customer"
    is_public     = true
    container     = 80
    host_port     = 80
    cpu           = 256
    memory        = 512
    desired_count = 1
    alb_target_group = {
      port              = 80
      protocol          = "HTTP"
      path_pattern      = ["/*"]
      health_check_path = "/health"
      priority          = 1
    }
  }
}

modules/ecs/ecs.tf #

resource "aws_ecs_service" "main" {
  for_each                           = var.service_config
  name                               = "${each.value.name}-Service-${var.env}"
  cluster                            = aws_ecs_cluster.main.id
  load_balancer {
    #target_group_arn = var.target_group_arn
    target_group_arn = var.alb_target_groups[each.key].arn
    container_name   = var.container_name
    container_port   = var.alb_container_port
  }
}

locals.tf #

locals {
  alb_target_groups = { for service, config in var.customer_config : service => config.alb_target_group }
}

问题根源 #

module.alb 模块并未对外输出 alb_target_groups 属性，导致在ecs模块中引用时找不到该属性。虽然你已经将local.alb_target_groups传递给alb模块作为输入，但模块默认不会自动输出输入变量，必须显式定义输出。

解决方案 #

1. 在alb模块中添加输出配置 #

在modules/alb/outputs.tf文件中添加以下输出，将创建的Target Group ARNs按服务名称映射输出：

output "alb_target_groups" {
  type = map(object({
    arn = string
  }))
  description = "Map of service names to their corresponding ALB Target Group ARNs"
  value = { for service_key, tg in aws_lb_target_group.main : service_key => { arn = tg.arn } }
}

2. 确保alb模块的Target Group使用for_each创建 #

检查modules/alb/alb.tf中的Target Group资源，必须基于var.alb_target_groups使用for_each创建，才能和服务名称一一对应：

resource "aws_lb_target_group" "main" {
  for_each = var.alb_target_groups

  name        = "${each.value.name}-${var.env}"
  port        = each.value.port
  protocol    = each.value.protocol
  vpc_id      = var.vpc_id
  target_type = "ip" # 根据你的ECS部署模式调整，Fargate用ip，EC2用instance

  health_check {
    path                = each.value.health_check_path
    protocol            = each.value.protocol
    matcher             = "200"
    interval            = 30
    timeout             = 5
    healthy_threshold   = 2
    unhealthy_threshold = 2
  }

  depends_on = [aws_lb_listener.main]
}

3. 验证ecs模块的变量定义 #

在modules/ecs/variables.tf中确保alb_target_groups变量类型正确：

variable "alb_target_groups" {
  type = map(object({
    arn = string
  }))
  description = "Map of service names to ALB Target Group ARNs"
}

完成以上修改后，重新执行terraform init和terraform plan，错误即可解决。

内容的提问来源于stack exchange，提问作者Vamsi