How do I write the terraform for an aws_autoscaling_policy for Step Scaling to set capacity units?

Question

The terraform for StepScaling is fairly limited for this resource. It includes terraform for removing and adding capacities, however, I am trying to set a number of capacities based on the lower and upper bounds of my Cloudwatch metric.

Essentially, I am trying to recreate and write up this resource (Dynamic Scaling Policy on Auto Scaling group) in terraform:

Policy type: Step Scaling
Scaling policy name: scale-out
CloudWatch alarm: my-sqs-alarm
Take the action: Set to
1 capacity units when 1 <= ApproximateNumberOfMessagesVisible < 6
2 capacity units when 6 <= ApproximateNumberOfMessagesVisible < 11
3 capacity units when 11 <= ApproximateNumberOfMessagesVisible < +infinity

This is what I have so far:

resource "aws_autoscaling_policy" "scale-out" {
  name                   = "scale-out"
  policy_type = "StepScaling"
  autoscaling_group_name = aws_autoscaling_group.autoscaler.name

How do I recreate my steps from the AWS console in terraform?

Answer 1

The solution is to set:

adjustment_type           = "ExactCapacity"

Then I got the configuration I wanted by writing:

step_adjustment {
    scaling_adjustment          = 1
    metric_interval_lower_bound = 0
    metric_interval_upper_bound = 5
  }

  step_adjustment {
    scaling_adjustment          = 2
    metric_interval_lower_bound = 5
    metric_interval_upper_bound = 10
  }

  step_adjustment {
    scaling_adjustment          = 3
    metric_interval_lower_bound = 10
  }