aws_lb_listener default action not storing group stickiness properties if there is only one target group in the forward action

[eric32490]

provider version: 3.49

I am currently using codedeploy to manage ECS Blue/Green Canary deployments
As I need to have stickiness enabled on the target groups, it also requires that the default action on the listener enables the "group stickiness", even during the times where there is only one target_group to be forwarded to

here is the code I wrote

resource "aws_lb_listener" "lb-listener" {
  load_balancer_arn = aws_lb.loadbalancer.arn
  port = 1443
  protocol = "HTTPS"
  ssl_policy = "ELBSecurityPolicy-TLS-1-2-2017-01"

  certificate_arn = var.lb_certificate_arn

  default_action {
    type = "forward"
    forward {
      target_group {
        arn = aws_lb_target_group.lb-tg.arn
        weight=1
      }

      stickiness {
        duration = 900
        enabled = true
      }
    }


  }

  lifecycle {
    ignore_changes = [
      default_action[0].target_group_arn
    ]
  }
}

Despite of this definition, terraform is simplifing the target groups definition and the result does not include stickness properties

terraform state show 'module.application-deploy-stage["gamma"].aws_lb_listener.lb-listener2'
# module.application-deploy-stage["gamma"].aws_lb_listener.lb-listener2:
resource "aws_lb_listener" "lb-listener2" {
    arn               = "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:listener/app/tf-lb-20210329094210037300000001/f5136585c1d718d5/cf278981636f3c5b"
    certificate_arn   = "arn:aws:acm:eu-central-1:xxyyzz227484:certificate/1934eccd-b61a-4fb2-ac6b-15f3d486023c"
    id                = "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:listener/app/tf-lb-20210329094210037300000001/f5136585c1d718d5/cf278981636f3c5b"
    load_balancer_arn = "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:loadbalancer/app/tf-lb-20210329094210037300000001/f5136585c1d718d5"
    port              = 1443
    protocol          = "HTTPS"
    ssl_policy        = "ELBSecurityPolicy-TLS-1-2-2017-01"
    tags              = {}
    tags_all          = {}

    default_action {
        order            = 1
        target_group_arn = "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:targetgroup/tf-20210329094425030600000002/fdd78d3fb3fdcca2"
        type             = "forward"
    }
}

As an example, here is an example definition I would like to have (TargetGroupStickinessConfig set with one target group)

aws elbv2 describe-listeners --load-balancer-arn arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:loadbalancer/app/tf-lb-20210715131729154400000001/e89f36189cb98518
{
    "Listeners": [
(..)            "DefaultActions": [
                {
                    "Type": "forward",
                    "TargetGroupArn": "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:targetgroup/tf-20210715132033934600000003/05a0898d2e0b4d80",
                    "Order": 1,
                    "ForwardConfig": {
                        "TargetGroups": [
                            {
                                "TargetGroupArn": "arn:aws:elasticloadbalancing:eu-central-1:xxyyzz227484:targetgroup/tf-20210715132033934600000003/05a0898d2e0b4d80",
                                "Weight": 1
                            }
                        ],
                        "TargetGroupStickinessConfig": {
                            "Enabled": true,
                            "DurationSeconds": 3600
                        }
                    }
                }
            ]
        }
    ]
}

[clint-truss]

I'm seeing this same behavior without the stickiness setting. Essentially, each time I have a ForwardConfig defined with one TargetGroup, after a TF apply, I can run a TF plan, and the ForwardConfig definition is removed and the Terraform in AWS is claims the state is:

default_action {
        order            = 1
        target_group_arn = "<targetarn>"
        type             = "forward"
    }

I can run an apply, which puts back my forward config, and then the next plan will show the drift again.

[gdavison]

Related to #22526

[github-actions]

This functionality has been released in v5.36.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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