Scheduled Scaling for Application Auto Scaling

Scaling based on a schedule allows you to set your own scaling schedule for predictable load changes. For example, every week the traffic to your web application starts to increase on Wednesday, remains high on Thursday, and starts to decrease on Friday. You can configure Application Auto Scaling to increase capacity on Wednesday and decrease capacity on Friday.

To use scheduled scaling, create scheduled actions, which tell Application Auto Scaling to perform scaling activities at specific times. When you create a scheduled action, you specify the scalable target, when the scaling activity should occur, and the minimum and maximum capacity. At the specified time, Application Auto Scaling scales based on the new capacity values.

Application Auto Scaling guarantees the order of execution for scheduled actions for the same scalable target but not for scheduled actions across scalable targets.

Register Scalable Target

Before you can create a scheduled action, you must register the scalable target. Use the register-scalable-target command to register a new scalable target.

The following example registers a Spot Fleet request with Application Auto Scaling. Application Auto Scaling can scale the number of instances in the Spot Fleet at a minimum of 2 instances and a maximum of 10.

aws application-autoscaling register-scalable-target --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --min-capacity 2 --max-capacity 10

Using the AWS CLI to Create or Update a Scheduled Action

You can create and update scheduled actions that scale one time only or that scale on a recurring schedule using the put-scheduled-action command. When you specify the new capacity, you can specify a minimum capacity, a maximum capacity, or both.

Schedule Actions for a One-Time Schedule

You can specify a one-time schedule to automatically scale your scalable target at a certain date and time, in UTC.

aws application-autoscaling put-scheduled-action --service-namespace ecs \
  --scalable-dimension ecs:service:DesiredCount \
  --resource-id service/default/web-app \
  --scheduled-action-name my-one-time-action \
  --schedule "at(2019-01-31T17:00:00)" \
  --scalable-target-action MaxCapacity=10

aws application-autoscaling put-scheduled-action --service-namespace custom-resource \
  --scalable-dimension custom-resource:ResourceType:Property \
  --resource-id file://~/custom-resource-id.txt \
  --scheduled-action-name my-one-time-action \
  --schedule "at(2019-03-31T22:00:00)" \
  --scalable-target-action MinCapacity=3

The custom-resource-id.txt file specifies the API Gateway endpoint for your custom resources. For more information about configuring a custom resource, see our GitHub repository. The contents of the file may look something like this:

https://example.execute-api.region.amazonaws.com/prod/scalableTargetDimensions/1-23456789

Schedule Actions on a Recurring Schedule

You can specify a recurrence schedule for a scheduled action using the --schedule option of the put-scheduled-action command. Application Auto Scaling supports cron and rate formats for schedule expressions. For more information, see Cron Expressions and Rate Expressions in the Amazon CloudWatch Events User Guide.

aws application-autoscaling put-scheduled-action --service-namespace dynamodb \
  --scalable-dimension dynamodb:table:WriteCapacityUnits \
  --resource-id table/my-table \
  --scheduled-action-name my-recurring-action \
  --schedule "cron(0 12 * * ? *)" \
  --scalable-target-action MinCapacity=10,MaxCapacity=50

aws application-autoscaling put-scheduled-action --service-namespace appstream \
  --scalable-dimension appstream:fleet:DesiredCapacity \
  --resource-id fleet/sample-fleet \
  --scheduled-action-name my-recurring-action \
  --schedule "rate(1 hour)" \
  --scalable-target-action MinCapacity=3,MaxCapacity=10

Describe Scheduled Actions

You can describe all scheduled actions for the specified service namespace using the following describe-scheduled-actions command.

aws application-autoscaling describe-scheduled-actions --service-namespace ecs

The following is example output.

{
    "ScheduledActions": [
        {
            "ScheduledActionARN": "<arn>",
            "ServiceNamespace": "ecs",
            "CreationTime": 1515026382.218,
            "ScalableDimension": "ecs:service:DesiredCount",
            "Schedule": "at(2018-01-31T17:00:00)",
            "ScalableTargetAction": {
                "MaxCapacity": 10
            },
            "ScheduledActionName": "my-one-time-action",
            "ResourceId": "service/default/web-app"
        }
    ]
}

Delete a Scheduled Action

When you are finished with a scheduled action, you can delete it using the delete-scheduled-action command.

The following command deletes the specified scheduled action for the specified scalable target.

aws application-autoscaling delete-scheduled-action --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --scheduled-action-name my-spot-fleet-action