[Enhancement]: Predictive scaling policies for ECS

[angusjellis]

Description

AWS recently announced a new feature: ECS Predictive Scaling Policies. They use the App Autoscaling API behind the scenes (according to the docs - see the CLI documentation).

It looks like this change would require adding PredictiveScaling as a valid option to Policy_Type.

A new predictive_scaling_configuration configuration block would also need to be added - perhaps taking as inspiration what has been set up for EC2 auto scaling.

Affected Resource(s) and/or Data Source(s)

aws_appautoscaling_policy

Potential Terraform Configuration

resource "aws_appautoscaling_policy" "ecs_policy" {
  name               = "PredictiveScalingPolicy"
  policy_type        = "PredictiveScaling"
  resource_id        = aws_appautoscaling_target.ecs_target.resource_id
  scalable_dimension = aws_appautoscaling_target.ecs_target.scalable_dimension
  service_namespace  = aws_appautoscaling_target.ecs_target.service_namespace

  predictive_scaling_configuration {
    metric_specifications =  [
        {
            target_value = 40,
            predefined_metric_pair_specification {
                predefined_metric_type =  "ECSServiceMemoryUtilization"
            }
        }
    ]
    scheduling_buffer_time =  3600
    max_capacity_breach_behavior =  "HonorMaxCapacity"
    mode = "ForecastOnly"
}
}

References

No response

Would you like to implement a fix?

Yes

[github-actions]

Community Note

Voting for Prioritization

• Please vote on this issue by adding a 👍 reaction to the original post to help the community and maintainers prioritize this request.
• Please see our prioritization guide for information on how we prioritize.
• Please do not leave "+1" or other comments that do not add relevant new information or questions, they generate extra noise for issue followers and do not help prioritize the request.

Volunteering to Work on This Issue

• If you are interested in working on this issue, please leave a comment.
• If this would be your first contribution, please review the contribution guide.

[angusjellis]

I would be interested in working on this myself, but I likely wouldn't be able to get started until this weekend.

[mcalsg]

Documentation from 5.78 is already mentioning those parameters :
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscalingplans_scaling_plan

But using it is failing on my side: ValidationException: Predictive Scaling is not supported for scalable dimension 'ecs:service:DesiredCount'

So i conclude that terraform 5.78 is not yet well handling PredictiveScaling configuration.
Warmly waiting for this enhancement then :-)

[mcalsg]

@angusjellis do you have an ETA for this enhancement to be done ?

Regards

[mcalsg]

Hi @angusjellis
Are you able to provide a feedback or estimate for this ?

[zahorniak]

Hey @mcalsg,

You can use awscc provider in the meantime:

resource "awscc_applicationautoscaling_scaling_policy" "predicted_scaling" {
  policy_name = "predicted_scaling"
  policy_type = "PredictiveScaling"

  service_namespace  = aws_appautoscaling_target.ecs_service_target.service_namespace
  resource_id        = aws_appautoscaling_target.ecs_service_target.resource_id
  scalable_dimension = aws_appautoscaling_target.ecs_service_target.scalable_dimension

  predictive_scaling_policy_configuration = {
    mode                         = "ForecastAndScale"
    max_capacity_breach_behavior = "HonorMaxCapacity"
    scheduling_buffer_time       = 600

    metric_specifications = [{
      target_value = var.target_latency

      customized_scaling_metric_specification = {
        metric_data_queries = [{
          id = "metric_id"
          metric_stat = {
            metric = {
              metric_name = "metric_name "
              namespace   = "metric_namespace"
              dimensions = [{
                name  = "dimension"
                value = 123
              }]
            }
            stat = "Average"
            unit = "Seconds"
          }
        }]
      }

      predefined_load_metric_specification = {
        predefined_metric_type = "ECSServiceTotalCPUUtilization"
      }
    }]
  }
}

[tlevilegalready]

Workaround no good? StatusMessage: No scalable target registered for service namespace: ecs