aws_lb_target_group_attachment does not register the EC2 instance to the target group after manually deregistered

[karlvlam]

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Terraform Version

Terraform v0.11.8

• provider.aws v1.32.0
• provider.template v1.0.0

Affected Resource(s)

• aws_lb_target_group_attachment

Terraform Configuration Files

resource "aws_lb" "mysetup" {
  name     = "${var.aws["env"]}-mysetup-alb"
  internal           = true 
  load_balancer_type = "application"
  security_groups = ["${var.mysetup["mysetup_lb_sg"]}"]
  subnets  = "${var.subnet_pub_id}"

  enable_deletion_protection = false 

}

resource "aws_lb_target_group" "mysetup" {
  name     = "${var.aws["env"]}-mysetup-lb-tg"
  port     = 3000 
  protocol = "HTTP"
  vpc_id   = "${var.aws["vpc_id"]}"

  deregistration_delay = 20
  target_type = "instance"

  health_check = {
    interval = 7 
    protocol = "HTTP"
    path = "/"
    port = "traffic-port" 
    timeout = 5
    healthy_threshold = 5
    unhealthy_threshold = 2
    matcher = "200,201" 
  }

}


resource "aws_lb_listener" "mysetup" {
  load_balancer_arn = "${aws_lb.mysetup.arn}"
  port              = "3000"
  protocol          = "HTTP"

  default_action {
    target_group_arn = "${aws_lb_target_group.mysetup.arn}"
    type             = "forward"
  }


}

data "template_file" "mysetup_nginx" {
  template = "${file("./cloudinit/mysetup.sh")}"
  vars {
    PUB_KEY = "${file("./cloudinit/public-keys")}"
  }
}


resource "aws_lb_target_group_attachment" "mysetup_grp1" {
  count = "${aws_instance.mysetup_grp1.count}" 
  target_group_arn = "${aws_lb_target_group.mysetup.arn}"
  target_id        = "${element(aws_instance.mysetup_grp1.*.id, count.index)}"
  port             = 3000

}

resource "aws_instance" "mysetup_grp1" {
  count = "${var.mysetup["mysetup_ec2_node_grp1_count"]}"
  ami = "${var.mysetup["mysetup_ec2_ami"]}"
  instance_type        = "${var.mysetup["mysetup_ec2_type"]}"
  user_data            = "${data.template_file.mysetup_nginx.rendered}"
  key_name             = "${var.mysetup["keypair"]}"
  iam_instance_profile = "${var.mysetup["mysetup_ec2_profile"]}"

  vpc_security_group_ids = ["${var.mysetup["mysetup_ec2_sg"]}"]
  subnet_id = "${element(var.subnet_pub_id, count.index)}"
  associate_public_ip_address = true
  root_block_device {
    delete_on_termination = true
    volume_type = "gp2"
    volume_size = 8 
  }

}

Expected Behavior

terraform plan should shows there are changes of the resources

Actual Behavior

terraform plan shows there are no changes of the resources

Steps to Reproduce

1. terraform apply
2. terraform plan shows no changes of the resources
3. remove an EC2 instances from the target group
4. terraform plan still shows no changes of the resources

[jwadolowski]

Experienced the same issue this morning.

$ terraform -v
Terraform v0.11.13
+ provider.aws v1.26.0
+ provider.null v1.0.0
+ provider.template v1.0.0

aws_alb_target_group_attachment.vertx-https-1 and aws_alb_target_group_attachment.vertx-http-1 have been removed from corresponding target groups by hand for the sake of debugging. terraform apply didn't reconnect them back.

$ terraform apply
data.terraform_remote_state.ci: Refreshing state...
data.terraform_remote_state.commons: Refreshing state...
...
aws_alb_target_group_attachment.vertx-http-0: Refreshing state... (ID: arn:aws:elasticloadbalancing:eu-west-2:...xyz-20190516134148151000000005)
aws_alb_target_group_attachment.vertx-https-0: Refreshing state... (ID: arn:aws:elasticloadbalancing:eu-west-2:...xyz-20190516134147904300000002)
aws_alb_target_group_attachment.vertx-https-1: Refreshing state... (ID: arn:aws:elasticloadbalancing:eu-west-2:...xyz-20190516134147939900000004)
aws_alb_target_group_attachment.vertx-http-1: Refreshing state... (ID: arn:aws:elasticloadbalancing:eu-west-2:...xyz-20190516134148219200000006)
...

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:
...

[dbachelder]

Is there a known reliable workaround for this? This is having a major impact on our ability to move forward with some new infrastructure plans.

[bflad]

The fix for this has been merged and will release with version 2.24.0 of the Terraform AWS Provider, later this week. Thanks to @Jamian for the implementation. 👍

[ghost]

This has been released in version 2.24.0 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 for triage. Thanks!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!