AWS负载均衡器Terraform模块(https://github.com/terraform-aws-modules/terraform-aws-alb)：target_group_index = 0，是什么？

Question

我尝试使用的模块，AWS应用和网络负载均衡器(ALB &北草坪会议大楼)平台模块，https://github.com/terraform-aws-modules/terraform-aws-alb。下面是应用程序负载均衡器的示例用法：

module "alb" {
  source  = "terraform-aws-modules/alb/aws"
  version = "~> 5.0"
  
  name = "my-alb"

  load_balancer_type = "application"

  vpc_id             = "vpc-abcde012"
  subnets            = ["subnet-abcde012", "subnet-bcde012a"]
  security_groups    = ["sg-edcd9784", "sg-edcd9785"]
  
  access_logs = {
    bucket = "my-alb-logs"
  }

  target_groups = [
    {
      name_prefix      = "pref-"
      backend_protocol = "HTTP"
      backend_port     = 80
      target_type      = "instance"
    }
  ]

  https_listeners = [
    {
      port               = 443
      protocol           = "HTTPS"
      certificate_arn    = "arn:aws:iam::123456789012:server-certificate/test_cert-123456789012"
      target_group_index = 0
    }
  ]

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

  tags = {
    Environment = "Test"
  }
}

我知道target_groups是一个数组。但是，为什么target_group_index =0而不是target_group_index =1或target_group_index = 2呢？指数0是多少？

Answer 1

在您发布的示例中，只有一个目标组 (TG)：

  target_groups = [
    {
      name_prefix      = "pref-"
      backend_protocol = "HTTP"
      backend_port     = 80
      target_type      = "instance"
    }
  ]

因此，侦听器使用target_group_index = 0来指示它们应用于这个特定的TG。如果您有更多的TGs，您将使用target_group_index = 1, 2, 3 ...来指定哪个侦听器应用于每个TG。