CPU Util based simple autoscaling heat HOT template

cpu_util heat HOT template example

heat_template_version: 2013-05-23

description: cpu_util based scale up or scale down. Please adjust thresholds below(in my case 0.65% cpu_util) to match cpu_util observed in your instances.
parameters:
  flavor:
    type: string
    description: Flavor for the instances to be created
    default: m1.nano
    constraints:
      - custom_constraint: nova.flavor
        description: Must be a flavor known to Nova
  image:
    type: string
    description: Image ID or image name to use for the server. Please find this under images horizon page.
    default: 23ed70af-d254-4b63-b488-cc94eb1a2add
    constraints:
      - custom_constraint: glance.image
        description: Must identify an image known to Glance

resources:
  asg:
    type: OS::Heat::AutoScalingGroup
    properties:
      resource:
        type: OS::Nova::Server
        properties:
            image: { get_param: image }
            flavor: { get_param: flavor }
            metadata: {"metering.stack": {get_param: "OS::stack_id"}}
      cooldown: 60
      desired_capacity: 2
      max_size: 3
      min_size: 1

  scale_up_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: { get_resource: asg }
      cooldown: 60
      scaling_adjustment: 1

  scale_down_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: { get_resource: asg }
      cooldown: 60
      scaling_adjustment: '-1'

  cpu_alarm_high:
    type: OS::Ceilometer::Alarm
    properties:
      meter_name: cpu_util
      statistic: avg
      period: 600
      evaluation_periods: 1
      threshold: 0.65
      alarm_actions:
        - {get_attr: [scale_up_policy, alarm_url]}
      comparison_operator: gt
      matching_metadata:
        'metadata.user_metadata.stack': {get_param: "OS::stack_id"}

  cpu_alarm_low:
    type: OS::Ceilometer::Alarm
    properties:
      meter_name: cpu_util
      statistic: avg
      period: 600
      evaluation_periods: 1
      threshold: 0.65
      alarm_actions:
        - {get_attr: [scale_down_policy, alarm_url]}
      comparison_operator: le
      matching_metadata:
        'metadata.user_metadata.stack': {get_param: "OS::stack_id"}

outputs:
  scale_up_url:
    description: This URL is the webhook to scale up the group.
    value: {get_attr: [scale_up_policy, alarm_url]}
  scale_dn_url:
    description: This URL is the webhook to scale down the group.
    value: {get_attr: [scale_down_policy, alarm_url]}