aws_appautoscaling_target update detaches any aws_appautoscaling_policy's

[charlesbjohnson]

Hi there,

Updating an aws_appautoscaling_target (which always forces a new resource) does not trigger dependent aws_appautoscaling_policys to be recreated. As a result, updating min_capacity or max_capacity causes all dependent aws_appautoscaling_policys to be deleted/detached, requiring a subsequent terraform apply to reattach them.

Terraform Version

v0.7.0+

Affected Resource(s)

• aws_appautoscaling_target
• aws_appautoscaling_policy

Terraform Configuration Files

provider "aws" {
  region = "us-west-2"
}

resource "aws_ecs_cluster" "cluster" {
  name = "demo-85e6a168597c3fe593b335df4c11496afe5dea31"
}

resource "aws_ecs_service" "service" {
  name = "${aws_ecs_cluster.cluster.name}"
  cluster = "${aws_ecs_cluster.cluster.id}"
  task_definition = "${aws_ecs_task_definition.task_definition.arn}"
  desired_count = 1
}

resource "aws_ecs_task_definition" "task_definition" {
  family = "nginx"
  container_definitions = <<EOF
[
  {
    "name": "nginx",
    "image": "nginx:latest",
    "cpu": 10,
    "memory": 500,
    "essential": true
  }
]
EOF
}

resource "aws_appautoscaling_target" "target" {
  name = "${aws_ecs_cluster.cluster.name}"
  service_namespace = "ecs"
  resource_id = "service/${aws_ecs_cluster.cluster.name}/${aws_ecs_service.service.name}"
  scalable_dimension = "ecs:service:DesiredCount"
  role_arn = "arn:aws:iam::428324370204:role/ecsAutoscaleRole"
  min_capacity = 1
  max_capacity = 2
}

resource "aws_appautoscaling_policy" "policy" {
  name = "${aws_appautoscaling_target.target.name}"
  resource_id = "service/${aws_ecs_cluster.cluster.name}/${aws_ecs_service.service.name}"
  adjustment_type = "ChangeInCapacity"
  cooldown = 300
  metric_aggregation_type = "Average"
  step_adjustment {
    metric_interval_lower_bound = 0
    scaling_adjustment = 1
  }
}

Expected Behavior

The aws_appautoscaling_target would be updated and the aws_appautoscaling_policy would still be attached.

Actual Behavior

The aws_appautoscaling_target was deleted and re-created, but the aws_appautoscaling_policy was lost in the process. A subsequent terraform apply will add it back, but it either should not have been removed or it should also have been recreated along with the aws_appautoscaling_target.

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. terraform apply
2. change aws_appautoscaling_target.target.max_capacity to 3
3. terraform apply (causes the policy detachment)
4. terraform apply (reattaches the policy)

Important Factoids

According to the AWS docs, the aws_appautoscaling_target can be created as well as updated via RegisterScalableTarget. Perhaps this could be used instead of recreating the aws_appautoscaling_target on update.

[redroot]

I just experienced this as well, +1

[mats16]

I also encountered this issue with v0.7.13

[yesteph]

Same issue with v0.8.1

[maxblaze]

We're seeing the same issue in v0.8.8.

[maxblaze]

Any update on this issue? This is still happening in v0.9.6 and is really critical for us.

[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 have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.