Terraform配置ECS关联ALB目标组报错及解决方案咨询

问题概述 #

• 配置aws_ecs_service的load_balancer块时，使用target_group_arns参数报错，提示需改用target_group_arn
• 改用target_group_arn后，引用module.alb.target_groups[0]报错，提示该模块无target_groups属性

原配置与报错信息 #

初始ECS服务配置 #

resource "aws_ecs_service" "nodejs-service" {
  name            = "nodejs-service"
  cluster         = aws_ecs_cluster.project_cluster.id
  task_definition = aws_ecs_task_definition.nodejs.arn
  launch_type     = "FARGATE"
  desired_count   = 1

  load_balancer {
    target_group_arns = module.alb.target_group_arns
    container_name   = "${aws_ecs_task_definition.nodejs.family}"
    container_port   = 8080 # Specifying the container port
  }

  network_configuration {
    subnets          = var.vpc.public_subnets
    assign_public_ip = true
  }
}

ALB模块配置 #

module "alb" {
  source             = "terraform-aws-modules/alb/aws"
  version            = "~> 8.0"
  name               = var.namespace
  load_balancer_type = "application"
  vpc_id             = var.vpc.vpc_id
  subnets            = var.vpc.public_subnets
  security_groups    = [var.sg.lb]

  http_tcp_listeners = [
    {
      port               = 80
      protocol           = "HTTP"
      target_group_index = 0
    }
  ]

  target_groups = [
    { name_prefix      = "nodejs-service"
      backend_protocol = "HTTP"
      backend_port     = 8080
      target_type      = "instance"
    }
  ]
}

报错信息1 #

│ Error: Unsupported argument
│
│   on modules/ecs/main.tf line 58, in resource "aws_ecs_service" "nodejs-service":
│   58:     target_group_arns = module.alb.target_group_arns
│
│ An argument named "target_group_arns" is not expected here. Did you mean "target_group_arn"?

修改后的配置片段 #

load_balancer {
    target_group_arn   = module.alb.target_groups[0]
    container_name   = "${aws_ecs_task_definition.nodejs.family}"
    container_port   = 8080 # Specifying the container port
  }

报错信息2 #

│ Error: Unsupported attribute
│
│   on modules/ecs/main.tf line 58, in resource "aws_ecs_service" "nodejs-service":
   58:     target_group_arn   = module.alb.target_groups[0]
     ├────────────────
     │ module.alb is a object

 This object does not have an attribute named "target_groups".

Terraform版本要求 #

terraform {
  required_version = ">= 1.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 4.27"
    }
    null = {
      source  = "hashicorp/null"
      version = ">= 2.0"
    }
  }
}

解决方案 #

1. 修正ECS负载均衡参数：aws_ecs_service的load_balancer块仅支持target_group_arn（单个目标组ARN），若需关联多个目标组，需添加多个load_balancer块。
2. 正确引用ALB模块输出：terraform-aws-modules/alb/aws 8.x版本的输出属性中，目标组ARN的列表为target_group_arns，因此引用第一个目标组ARN应使用module.alb.target_group_arns[0]。

修正后的ECS服务配置 #

resource "aws_ecs_service" "nodejs-service" {
  name            = "nodejs-service"
  cluster         = aws_ecs_cluster.project_cluster.id
  task_definition = aws_ecs_task_definition.nodejs.arn
  launch_type     = "FARGATE"
  desired_count   = 1

  load_balancer {
    target_group_arn = module.alb.target_group_arns[0]
    container_name   = aws_ecs_task_definition.nodejs.family
    container_port   = 8080
  }

  network_configuration {
    subnets          = var.vpc.public_subnets
    assign_public_ip = true
  }
}

额外优化建议 #

• 由于使用FARGATE启动类型，建议将ALB模块中target_groups的target_type修改为ip，因为Fargate任务没有EC2实例ID，使用ip才能正确将任务IP注册到目标组。
• 确保ALB安全组允许80端口的外部入站流量，ECS任务所在安全组允许来自ALB安全组的8080端口流量。

内容的提问来源于stack exchange，提问作者Ahmed Omar