speller commented 1 year ago

Terraform Core Version

1.5.0

AWS Provider Version

4.67.0

Affected Resource(s)

aws_autoscaling_policy

Expected Behavior

aws_autoscaling_policy resources are handled properly.

Actual Behavior

I'm getting the following errors randomly:

│ Error: creating Auto Scaling Policy (CPUUtilizationInt): ValidationError: Only one TargetTrackingScaling policy for a given metric specification is allowed.
│   status code: 400, request id: e9a2c4c1-bc7d-4aae-b2f7-f6998ed196ee
│ 
│   with module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization_int[0],
│   on .terraform/modules/service-bff.instance/main.tf line 77, in resource "aws_autoscaling_policy" "cpu_utilization_int":
│   77: resource "aws_autoscaling_policy" "cpu_utilization_int" {
│ 
╵

Relevant Error/Panic Output Snippet

No response

Terraform Configuration Files

I have the following configurations for autoscaling policies:

resource "aws_autoscaling_policy" "requests_count" {
  count = var.as_requests_count > 0 ? 1 : 0
  autoscaling_group_name = aws_autoscaling_group.service.name
  name = "AVGRequestsCount"
  policy_type = "TargetTrackingScaling"
  estimated_instance_warmup = var.instance_warmup_time
  target_tracking_configuration {
    predefined_metric_specification {
      predefined_metric_type = "ALBRequestCountPerTarget"
      resource_label = local.asg_resource_label
    }
    target_value = var.as_requests_count
  }
}

resource "aws_autoscaling_policy" "requests_count_int" {
  count = var.use_internal_lb ? (var.as_requests_count > 0 ? 1 : 0) : 0
  autoscaling_group_name = aws_autoscaling_group.service.name
  name = "AVGRequestsCountInt"
  policy_type = "TargetTrackingScaling"
  estimated_instance_warmup = var.instance_warmup_time
  target_tracking_configuration {
    predefined_metric_specification {
      predefined_metric_type = "ALBRequestCountPerTarget"
      resource_label = local.asg_resource_label_int
    }
    target_value = var.as_requests_count
  }
}

resource "aws_autoscaling_policy" "cpu_utilization" {
  count = var.as_cpu_utilization > 0 ? 1 : 0
  autoscaling_group_name = aws_autoscaling_group.service.name
  name = "CPUUtilization"
  policy_type = "TargetTrackingScaling"
  estimated_instance_warmup = var.instance_warmup_time
  target_tracking_configuration {
    predefined_metric_specification {
      predefined_metric_type = "ASGAverageCPUUtilization"
    }
    target_value = var.as_cpu_utilization
  }
}

resource "aws_autoscaling_policy" "cpu_utilization_int" {
  count = var.use_internal_lb ? (var.as_cpu_utilization > 0 ? 1 : 0) : 0
  autoscaling_group_name = aws_autoscaling_group.service.name
  name = "CPUUtilizationInt"
  policy_type = "TargetTrackingScaling"
  estimated_instance_warmup = var.instance_warmup_time
  target_tracking_configuration {
    predefined_metric_specification {
      predefined_metric_type = "ASGAverageCPUUtilization"
    }
    target_value = var.as_cpu_utilization
  }
}

Steps to Reproduce

Unknown

Debug Output

No response

Panic Output

No response

Important Factoids

The issue happens randomly when I'm updating an existing configuration. During the plan, it looks like it misses one of the policies from the plan and doesn't refresh it:

module.service-bff.module.instance.aws_autoscaling_policy.requests_count_int[0]: Refreshing state... [id=AVGRequestsCountInt]
module.service-bff.module.instance.aws_autoscaling_policy.requests_count[0]: Refreshing state... [id=AVGRequestsCount]
module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization[0]: Refreshing state... [id=CPUUtilization]

Then, it plans to add the "missing" policy:

  # module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization_int[0] will be created
  + resource "aws_autoscaling_policy" "cpu_utilization_int" {
      + arn                       = (known after apply)
      + autoscaling_group_name    = "rev_f_9335_bf-1-2023111503403646740000001e"
      + enabled                   = true
      + estimated_instance_warmup = 120
      + id                        = (known after apply)
      + metric_aggregation_type   = (known after apply)
      + name                      = "CPUUtilizationInt"
      + policy_type               = "TargetTrackingScaling"
      + target_tracking_configuration {
          + disable_scale_in = false
          + target_value     = 70
          + predefined_metric_specification {
              + predefined_metric_type = "ASGAverageCPUUtilization"
            }
        }
    }

And on the apply, it fails with the message above because the policy already exists (see above).

I don't do manual changes to the infrastructure. And the issue is happening randomly. Sometimes everything is fine, sometimes not on the same configuration.

How to fix it?

References

No response

Would you like to implement a fix?

None

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speller commented 1 year ago

I've checked one of the recent failing deployments, and found that the issue happens during the initial resource creation. Below are pieces of logs from the work on an empty state (completely new deployment).

Everything is looking good on the plan:

# module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization[0]will be created
  resource "aws_autoscaling_policy" "cpu_utilization" {
       arn                       = (known after apply)
       autoscaling_group_name    = (known after apply)
       enabled                   = true
       estimated_instance_warmup = 120
       id                        = (known after apply)
       metric_aggregation_type   = (known after apply)
       name                      = "CPUUtilization"
       policy_type               = "TargetTrackingScaling"

       target_tracking_configuration {
           disable_scale_in = false
           target_value     = 70

           predefined_metric_specification {
               predefined_metric_type = "ASGAverageCPUUtilization"
            }
        }
    }

# module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization_int[0]will be created
  resource "aws_autoscaling_policy" "cpu_utilization_int" {
       arn                       = (known after apply)
       autoscaling_group_name    = (known after apply)
       enabled                   = true
       estimated_instance_warmup = 120
       id                        = (known after apply)
       metric_aggregation_type   = (known after apply)
       name                      = "CPUUtilizationInt"
       policy_type               = "TargetTrackingScaling"

       target_tracking_configuration {
           disable_scale_in = false
           target_value     = 70

           predefined_metric_specification {
               predefined_metric_type = "ASGAverageCPUUtilization"
            }
        }
    }

# module.service-bff.module.instance.aws_autoscaling_policy.requests_count[0]will be created
  resource "aws_autoscaling_policy" "requests_count" {
       arn                       = (known after apply)
       autoscaling_group_name    = (known after apply)
       enabled                   = true
       estimated_instance_warmup = 120
       id                        = (known after apply)
       metric_aggregation_type   = (known after apply)
       name                      = "AVGRequestsCount"
       policy_type               = "TargetTrackingScaling"

       target_tracking_configuration {
           disable_scale_in = false
           target_value     = 21

           predefined_metric_specification {
               predefined_metric_type = "ALBRequestCountPerTarget"
               resource_label         = (known after apply)
            }
        }
    }

# module.service-bff.module.instance.aws_autoscaling_policy.requests_count_int[0]will be created
  resource "aws_autoscaling_policy" "requests_count_int" {
       arn                       = (known after apply)
       autoscaling_group_name    = (known after apply)
       enabled                   = true
       estimated_instance_warmup = 120
       id                        = (known after apply)
       metric_aggregation_type   = (known after apply)
       name                      = "AVGRequestsCountInt"
       policy_type               = "TargetTrackingScaling"

       target_tracking_configuration {
           disable_scale_in = false
           target_value     = 21

           predefined_metric_specification {
               predefined_metric_type = "ALBRequestCountPerTarget"
               resource_label         = (known after apply)
            }
        }
    }

In the application, it looks ok in the beginning:

module.service-bff.module.instance.aws_autoscaling_policy.requests_count_int[0]: Creating...
module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization_int[0]: Creating...
module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization[0]: Creating...
module.service-bff.module.instance.aws_autoscaling_policy.requests_count[0]: Creating...

But then, only three are reporting the success:

module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization[0]: Creation complete after 1s [id=CPUUtilization]
module.service-bff.module.instance.aws_autoscaling_policy.requests_count[0]: Creation complete after 1s [id=AVGRequestsCount]
module.service-bff.module.instance.aws_autoscaling_policy.requests_count_int[0]: Creation complete after 1s [id=AVGRequestsCountInt]

And eventually the following error is thrown:

│ Error: creating Auto Scaling Policy (CPUUtilizationInt): ValidationError: Only one TargetTrackingScaling policy for a given metric specification is allowed.
│   status code: 400, request id: 26e35a65-648d-4ac8-a45e-d93f85ab2579
│ 
│   with module.service-bff.module.instance.aws_autoscaling_policy.cpu_utilization_int[0],
│   on .terraform/modules/service-bff.instance/main.tf line 77, in resource "aws_autoscaling_policy" "cpu_utilization_int":
│   77: resource "aws_autoscaling_policy" "cpu_utilization_int" {
│

Here is the issue - somewhere the target policy is created twice and this makes TF failing on already existing resource. Nobody except TF was able to create this resource because there was nothing.

When I check the problematic autoscaling group, I can see three policies created. I delete them all and on the next run TF succeeds.

speller commented 1 year ago

Probably, this is a problem in our configuration but there's a bug on the AWS side that allows creating two ASGAverageCPUUtilization policies under some circumstances... Our autoscaling groups are targeted by two load balancers, and for ALBRequestCountPerTarget it is okay to have two policies. But ASGAverageCPUUtilization is not dependent on load balancers so it should be only one but I copypasted the config and accidentally duplicated ASGAverageCPUUtilization. And somehow it worked for a long time already in the majority of cases.

speller commented 1 year ago

Here is an example of a working case when all four are created:

hashicorp / terraform-provider-aws

[Bug]: aws_autoscaling_policy is often missed from the plan or state #34408

Terraform Core Version

AWS Provider Version

Affected Resource(s)

Expected Behavior

Actual Behavior

Relevant Error/Panic Output Snippet

Terraform Configuration Files

Steps to Reproduce

Debug Output

Panic Output

Important Factoids

References

Would you like to implement a fix?

Community Note