Get ID of AWS Security Group Terraform Module - amazon-web-services

Question

I used this module to create a security group inside a VPC. One of the outputs is the security_group_id, but I'm getting this error:
│ Error: Unsupported attribute
│
│ on ecs.tf line 39, in resource "aws_ecs_service" "hello_world":
│ 39: security_groups = [module.app_security_group.security_group_id]
│ ├────────────────
│ │ module.app_security_group is a object, known only after apply
│
│ This object does not have an attribute named "security_group_id".
I need the security group for an ECS service:
resource "aws_ecs_service" "hello_world" {
name = "hello-world-service"
cluster = aws_ecs_cluster.container_service_cluster.id
task_definition = aws_ecs_task_definition.hello_world.arn
desired_count = 1
launch_type = "FARGATE"
network_configuration {
security_groups = [module.app_security_group.security_group_id]
subnets = module.vpc.private_subnets
}
load_balancer {
target_group_arn = aws_lb_target_group.loadbalancer_target_group.id
container_name = "hello-world-app"
container_port = 3000
}
depends_on = [aws_lb_listener.loadbalancer_listener, module.app_security_group]
}
I understand that I can only know the security group ID after it is created. That's why I added the depends_on part on the ECS stanza, but it kept returning the same error.
Update
I specified count as 1 on the app_security_group module and this is the error I'm getting now.
│ Error: Unsupported attribute
│
│ on ecs.tf line 39, in resource "aws_ecs_service" "hello_world":
│ 39: security_groups = module.app_security_group.security_group_id
│ ├────────────────
│ │ module.app_security_group is a list of object, known only after apply
│
│ Can't access attributes on a list of objects. Did you mean to access an attribute for a specific element of the list, or across all elements of the list?
Update II
This is the module declaration:
module "app_security_group" {
source = "terraform-aws-modules/security-group/aws//modules/web"
version = "3.17.0"
name = "${var.project}-web-sg"
description = "Security group for web-servers with HTTP ports open within VPC"
vpc_id = module.vpc.vpc_id
# ingress_cidr_blocks = module.vpc.public_subnets_cidr_blocks
ingress_cidr_blocks = ["0.0.0.0/0"]
}

Answer 1

I took a look at that module. The problem is that the version 3.17.0 of the module simply does not have the output of security_group_id. You are using a really old version.
The latest version from the site is 4.7.0, you would want to upgrade to this one. In fact, any version above 4.0.0 has the security_group_id, so you need to at least 4.0.0.

Answer 2

As you are using count, please try below.
network_configuration {
security_groups = [module.app_security_group[0].security_group_id]
subnets = module.vpc.private_subnets
}