I have an AWS ALB that is supposed to frontend an ECS Fargate frontend app written in Angular and a Backend that is written in NestJS. I intend to use a Single ALB for both frontend and backend and therefore, I have setup a listener rule that should take about 7 backend condition rules which are path patterns.

The error I get when I try to deploy this app is:-

updating ECS Service InvalidParameterException: load balancers can have at most 5 items.
I know the limit is about 100 items from the AWS documentation.

I have this Terraform code that is supposed to provision the infrastructure:-

resource "aws_ecs_service" "ecs_service_def" {
  name            = "backend-service"
  task_definition = "${aws_ecs_task_definition.ecs_task_def.family}"
  desired_count   = 1
  force_new_deployment = true
  health_check_grace_period_seconds  = 300
  launch_type     = "FARGATE"
  cluster         = data.aws_ecs_cluster.this.id
  depends_on      = [
    aws_iam_role_policy.ecs_service_role_policy,
    data.aws_alb_listener.selected443
  ]
  deployment_circuit_breaker {
    enable = true
    rollback = true
  }
  network_configuration {
    security_groups = ["sg-0233333337779"]
    subnets         = var.db_subnet_ids
  }

  load_balancer {
    target_group_arn = aws_alb_target_group.upload.arn
    container_name   = "backend"
    container_port   = "3000"
  }

  load_balancer {
    target_group_arn = aws_alb_target_group.search-logs.arn
    container_name   = "backend"
    container_port   = "3000"
  }

  load_balancer {
    target_group_arn = aws_alb_target_group.log-file-info.arn
    container_name   = "backend"
    container_port   = "3000"
  }


  dynamic "load_balancer" {
    for_each = local.ecs_load_balancers
    content {
      container_name   = load_balancer.value.container_name
      container_port   = load_balancer.value.container_port
      target_group_arn = load_balancer.value.target_group_arn
    }
  }   
}

locals {
  ecs_load_balancers = [
  {
    container_name   = "backend"
    container_port   = "3000"
    target_group_arn = aws_alb_target_group.download.arn
  },
  {
    container_name   = "backend"
    container_port   = "3000"
    target_group_arn = aws_alb_target_group.update-log-status.arn
  },
  {
    container_name   = "backend"
    container_port   = "3000"
    target_group_arn = aws_alb_target_group.log-upload-info.arn
  },
  {
    container_name   = "backend"
    container_port   = "3000"
    target_group_arn = aws_alb_target_group.recent-logs.arn
  }]
}

I am using dynamic block to provision the remaining rules but no matter whatever change I make to the Terraform logic, the “apply” action always errors out with the given message.

Appreciate if anyone can share a solution to this issue.