Unable to attach alb to nodes autoscaling group

[olibenni]

Description

Using aws_autoscaling_attachment to attach alb target group arn with out autoscaling group for the nodes in the eks only works on every other apply. The apply is successful but the attachment is removed on every other apply.

• [x] ✋ I have searched the open/closed issues and my issue is not listed.

Versions

• Module version [Required]: 4.6.2

Reproduction Code [Required]

module "eks_blueprints" {
  source = "github.com/aws-ia/terraform-aws-eks-blueprints?ref=v4.6.2"

  cluster_version    = "1.21"
  vpc_id             = var.vpc_id
  private_subnet_ids = var.subnet_ids
  cluster_name       = "somecluster-eks"

  self_managed_node_groups = {
    self_mg5 = {
      node_group_name    = "self_mg5"
      instance_type      = "m5.large"
      launch_template_os = "amazonlinux2eks"
      subnet_ids         = var.worker_subnet_ids
      public_ip          = true
      # This is an invalid argument at the moment
      # target_group_arns  = [var.aws_lb_target_group_arn]
  }
}

resource "aws_autoscaling_attachment" "asg_attachment_bar" {
  autoscaling_group_name = module.eks_blueprints.self_managed_node_group_autoscaling_groups[0]
  alb_target_group_arn   = var.aws_lb_target_group_arn
}

Expected behavior

Expect new nodes need be be part of our target group The autoscaling group in the eks cluster needs to be aware of the target group so that new nodes are part of it

Actual behavior

When we first apply, the attachment is made and things work fine. But in our subsequent apply, the eks_blueprint notices an attachment that isn't defined in the blueprint so it removes it.

[askulkarni2]

@olibenni out of curiosity, what is your use-case to attach an ALB directly to the ASG this way?

[olibenni]

Good question, I wanted to add a loadbalancer for the ArgoCD server, exposing the ArgoCD web ui. Open to alternatives.

[askulkarni2]

Gotcha. What you are trying to do will certainly work but its more common to use an Ingress configuration for such purposes. An Ingress controller such as AWS Load Balancer Controller makes it easier to manage Elastic Load Balancers for a Kubernetes cluster from within the cluster. Checkout our example which shows how you can configure a complete Ingress path with a combination of ingress-nginx, LBC, external-dns. You can repurpose this example for serving of the ArgoCD UI.

[olibenni]

Thanks for the tip! Will check this out better tomorrow (working on UTC time).

[bryantbiggs]

closed in #855