Auto Scaling

Gets information about the scheduled actions that haven't run or that have not reached their end time. To describe the scaling activities for scheduled actions that have already run, call the DescribeScalingActivities API.

Describes the specified tags. You can use filters to limit the results. For example, you can query for the tags for a specific Auto Scaling group. You can specify multiple values for a filter. A tag must match at least one of the specified values for it to be included in the results. You can also specify multiple filters. The result includes information for a particular tag only if it matches all the filters. If there's no match, no special message is returned. For more information, see Tag Auto Scaling groups and instances in the Amazon EC2 Auto Scaling User Guide.

Describes the termination policies supported by Amazon EC2 Auto Scaling. For more information, see Work with Amazon EC2 Auto Scaling termination policies in the Amazon EC2 Auto Scaling User Guide.

Gets information about the traffic sources for the specified Auto Scaling group. You can optionally provide a traffic source type. If you provide a traffic source type, then the results only include that traffic source type. If you do not provide a traffic source type, then the results include all the traffic sources for the specified Auto Scaling group.

Gets information about a warm pool and its instances. For more information, see Warm pools for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide.

Removes one or more instances from the specified Auto Scaling group. After the instances are detached, you can manage them independent of the Auto Scaling group. If you do not specify the option to decrement the desired capacity, Amazon EC2 Auto Scaling launches instances to replace the ones that are detached. If there is a Classic Load Balancer attached to the Auto Scaling group, the instances are deregistered from the load balancer. If there are target groups attached to the Auto Scaling group, the instances are deregistered from the target groups. For more information, see Detach EC2 instances from your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

This API operation is superseded by DetachTrafficSources, which can detach multiple traffic sources types. We recommend using DetachTrafficSources to simplify how you manage traffic sources. However, we continue to support DetachLoadBalancerTargetGroups. You can use both the original DetachLoadBalancerTargetGroups API operation and DetachTrafficSources on the same Auto Scaling group. Detaches one or more target groups from the specified Auto Scaling group. When you detach a target group, it enters the Removing state while deregistering the instances in the group. When all instances are deregistered, then you can no longer describe the target group using the DescribeLoadBalancerTargetGroups API call. The instances remain running. You can use this operation to detach target groups that were attached by using AttachLoadBalancerTargetGroups, but not for target groups that were attached by using AttachTrafficSources.

This API operation is superseded by DetachTrafficSources, which can detach multiple traffic sources types. We recommend using DetachTrafficSources to simplify how you manage traffic sources. However, we continue to support DetachLoadBalancers. You can use both the original DetachLoadBalancers API operation and DetachTrafficSources on the same Auto Scaling group. Detaches one or more Classic Load Balancers from the specified Auto Scaling group. This operation detaches only Classic Load Balancers. If you have Application Load Balancers, Network Load Balancers, or Gateway Load Balancers, use the DetachLoadBalancerTargetGroups API instead. When you detach a load balancer, it enters the Removing state while deregistering the instances in the group. When all instances are deregistered, then you can no longer describe the load balancer using the DescribeLoadBalancers API call. The instances remain running.

Detaches one or more traffic sources from the specified Auto Scaling group. When you detach a taffic, it enters the Removing state while deregistering the instances in the group. When all instances are deregistered, then you can no longer describe the traffic source using the DescribeTrafficSources API call. The instances continue to run.

Disables group metrics collection for the specified Auto Scaling group.

Enables group metrics collection for the specified Auto Scaling group. You can use these metrics to track changes in an Auto Scaling group and to set alarms on threshold values. You can view group metrics using the Amazon EC2 Auto Scaling console or the CloudWatch console. For more information, see Monitor CloudWatch metrics for your Auto Scaling groups and instances in the Amazon EC2 Auto Scaling User Guide.

Moves the specified instances into the standby state. If you choose to decrement the desired capacity of the Auto Scaling group, the instances can enter standby as long as the desired capacity of the Auto Scaling group after the instances are placed into standby is equal to or greater than the minimum capacity of the group. If you choose not to decrement the desired capacity of the Auto Scaling group, the Auto Scaling group launches new instances to replace the instances on standby. For more information, see Temporarily removing instances from your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

Executes the specified policy. This can be useful for testing the design of your scaling policy.

Moves the specified instances out of the standby state. After you put the instances back in service, the desired capacity is incremented. For more information, see Temporarily removing instances from your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

Retrieves the forecast data for a predictive scaling policy. Load forecasts are predictions of the hourly load values using historical load data from CloudWatch and an analysis of historical trends. Capacity forecasts are represented as predicted values for the minimum capacity that is needed on an hourly basis, based on the hourly load forecast. A minimum of 24 hours of data is required to create the initial forecasts. However, having a full 14 days of historical data results in more accurate forecasts. For more information, see Predictive scaling for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide.

Creates or updates a lifecycle hook for the specified Auto Scaling group. Lifecycle hooks let you create solutions that are aware of events in the Auto Scaling instance lifecycle, and then perform a custom action on instances when the corresponding lifecycle event occurs. This step is a part of the procedure for adding a lifecycle hook to an Auto Scaling group: (Optional) Create a launch template or launch configuration with a user data script that runs while an instance is in a wait state due to a lifecycle hook. (Optional) Create a Lambda function and a rule that allows Amazon EventBridge to invoke your Lambda function when an instance is put into a wait state due to a lifecycle hook. (Optional) Create a notification target and an IAM role. The target can be either an Amazon SQS queue or an Amazon SNS topic. The role allows Amazon EC2 Auto Scaling to publish lifecycle notifications to the target. Create the lifecycle hook. Specify whether the hook is used when the instances launch or terminate. If you need more time, record the lifecycle action heartbeat to keep the instance in a wait state using the RecordLifecycleActionHeartbeat API call. If you finish before the timeout period ends, send a callback by using the CompleteLifecycleAction API call. For more information, see Amazon EC2 Auto Scaling lifecycle hooks in the Amazon EC2 Auto Scaling User Guide. If you exceed your maximum limit of lifecycle hooks, which by default is 50 per Auto Scaling group, the call fails. You can view the lifecycle hooks for an Auto Scaling group using the DescribeLifecycleHooks API call. If you are no longer using a lifecycle hook, you can delete it by calling the DeleteLifecycleHook API.

Configures an Auto Scaling group to send notifications when specified events take place. Subscribers to the specified topic can have messages delivered to an endpoint such as a web server or an email address. This configuration overwrites any existing configuration. For more information, see Getting Amazon SNS notifications when your Auto Scaling group scales in the Amazon EC2 Auto Scaling User Guide. If you exceed your maximum limit of SNS topics, which is 10 per Auto Scaling group, the call fails.

Creates or updates a scaling policy for an Auto Scaling group. Scaling policies are used to scale an Auto Scaling group based on configurable metrics. If no policies are defined, the dynamic scaling and predictive scaling features are not used. For more information about using dynamic scaling, see Target tracking scaling policies and Step and simple scaling policies in the Amazon EC2 Auto Scaling User Guide. For more information about using predictive scaling, see Predictive scaling for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide. You can view the scaling policies for an Auto Scaling group using the DescribePolicies API call. If you are no longer using a scaling policy, you can delete it by calling the DeletePolicy API.

Creates or updates a scheduled scaling action for an Auto Scaling group. For more information, see Scheduled scaling in the Amazon EC2 Auto Scaling User Guide. You can view the scheduled actions for an Auto Scaling group using the DescribeScheduledActions API call. If you are no longer using a scheduled action, you can delete it by calling the DeleteScheduledAction API. If you try to schedule your action in the past, Amazon EC2 Auto Scaling returns an error message.

Creates or updates a warm pool for the specified Auto Scaling group. A warm pool is a pool of pre-initialized EC2 instances that sits alongside the Auto Scaling group. Whenever your application needs to scale out, the Auto Scaling group can draw on the warm pool to meet its new desired capacity. For more information and example configurations, see Warm pools for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide. This operation must be called from the Region in which the Auto Scaling group was created. This operation cannot be called on an Auto Scaling group that has a mixed instances policy or a launch template or launch configuration that requests Spot Instances. You can view the instances in the warm pool using the DescribeWarmPool API call. If you are no longer using a warm pool, you can delete it by calling the DeleteWarmPool API.

Records a heartbeat for the lifecycle action associated with the specified token or instance. This extends the timeout by the length of time defined using the PutLifecycleHook API call. This step is a part of the procedure for adding a lifecycle hook to an Auto Scaling group: (Optional) Create a launch template or launch configuration with a user data script that runs while an instance is in a wait state due to a lifecycle hook. (Optional) Create a Lambda function and a rule that allows Amazon EventBridge to invoke your Lambda function when an instance is put into a wait state due to a lifecycle hook. (Optional) Create a notification target and an IAM role. The target can be either an Amazon SQS queue or an Amazon SNS topic. The role allows Amazon EC2 Auto Scaling to publish lifecycle notifications to the target. Create the lifecycle hook. Specify whether the hook is used when the instances launch or terminate. If you need more time, record the lifecycle action heartbeat to keep the instance in a wait state. If you finish before the timeout period ends, send a callback by using the CompleteLifecycleAction API call. For more information, see Amazon EC2 Auto Scaling lifecycle hooks in the Amazon EC2 Auto Scaling User Guide.

Resumes the specified suspended auto scaling processes, or all suspended process, for the specified Auto Scaling group. For more information, see Suspending and resuming scaling processes in the Amazon EC2 Auto Scaling User Guide.

Cancels an instance refresh that is in progress and rolls back any changes that it made. Amazon EC2 Auto Scaling replaces any instances that were replaced during the instance refresh. This restores your Auto Scaling group to the configuration that it was using before the start of the instance refresh. This operation is part of the instance refresh feature in Amazon EC2 Auto Scaling, which helps you update instances in your Auto Scaling group after you make configuration changes. A rollback is not supported in the following situations: There is no desired configuration specified for the instance refresh. The Auto Scaling group has a launch template that uses an Amazon Web Services Systems Manager parameter instead of an AMI ID for the ImageId property. The Auto Scaling group uses the launch template's $Latest or $Default version. When you receive a successful response from this operation, Amazon EC2 Auto Scaling immediately begins replacing instances. You can check the status of this operation through the DescribeInstanceRefreshes API operation.

Sets the size of the specified Auto Scaling group. If a scale-in activity occurs as a result of a new DesiredCapacity value that is lower than the current size of the group, the Auto Scaling group uses its termination policy to determine which instances to terminate. For more information, see Manual scaling in the Amazon EC2 Auto Scaling User Guide.

Sets the health status of the specified instance. For more information, see Health checks for Auto Scaling instances in the Amazon EC2 Auto Scaling User Guide.

Updates the instance protection settings of the specified instances. This operation cannot be called on instances in a warm pool. For more information about preventing instances that are part of an Auto Scaling group from terminating on scale in, see Using instance scale-in protection in the Amazon EC2 Auto Scaling User Guide. If you exceed your maximum limit of instance IDs, which is 50 per Auto Scaling group, the call fails.

Starts an instance refresh. During an instance refresh, Amazon EC2 Auto Scaling performs a rolling update of instances in an Auto Scaling group. Instances are terminated first and then replaced, which temporarily reduces the capacity available within your Auto Scaling group. This operation is part of the instance refresh feature in Amazon EC2 Auto Scaling, which helps you update instances in your Auto Scaling group. This feature is helpful, for example, when you have a new AMI or a new user data script. You just need to create a new launch template that specifies the new AMI or user data script. Then start an instance refresh to immediately begin the process of updating instances in the group. If successful, the request's response contains a unique ID that you can use to track the progress of the instance refresh. To query its status, call the DescribeInstanceRefreshes API. To describe the instance refreshes that have already run, call the DescribeInstanceRefreshes API. To cancel an instance refresh that is in progress, use the CancelInstanceRefresh API. An instance refresh might fail for several reasons, such as EC2 launch failures, misconfigured health checks, or not ignoring or allowing the termination of instances that are in Standby state or protected from scale in. You can monitor for failed EC2 launches using the scaling activities. To find the scaling activities, call the DescribeScalingActivities API. If you enable auto rollback, your Auto Scaling group will be rolled back automatically when the instance refresh fails. You can enable this feature before starting an instance refresh by specifying the AutoRollback property in the instance refresh preferences. Otherwise, to roll back an instance refresh before it finishes, use the RollbackInstanceRefresh API.

Suspends the specified auto scaling processes, or all processes, for the specified Auto Scaling group. If you suspend either the Launch or Terminate process types, it can prevent other process types from functioning properly. For more information, see Suspending and resuming scaling processes in the Amazon EC2 Auto Scaling User Guide. To resume processes that have been suspended, call the ResumeProcesses API.

Terminates the specified instance and optionally adjusts the desired group size. This operation cannot be called on instances in a warm pool. This call simply makes a termination request. The instance is not terminated immediately. When an instance is terminated, the instance status changes to terminated. You can't connect to or start an instance after you've terminated it. If you do not specify the option to decrement the desired capacity, Amazon EC2 Auto Scaling launches instances to replace the ones that are terminated. By default, Amazon EC2 Auto Scaling balances instances across all Availability Zones. If you decrement the desired capacity, your Auto Scaling group can become unbalanced between Availability Zones. Amazon EC2 Auto Scaling tries to rebalance the group, and rebalancing might terminate instances in other zones. For more information, see Rebalancing activities in the Amazon EC2 Auto Scaling User Guide.

We strongly recommend that all Auto Scaling groups use launch templates to ensure full functionality for Amazon EC2 Auto Scaling and Amazon EC2. Updates the configuration for the specified Auto Scaling group. To update an Auto Scaling group, specify the name of the group and the property that you want to change. Any properties that you don't specify are not changed by this update request. The new settings take effect on any scaling activities after this call returns. If you associate a new launch configuration or template with an Auto Scaling group, all new instances will get the updated configuration. Existing instances continue to run with the configuration that they were originally launched with. When you update a group to specify a mixed instances policy instead of a launch configuration or template, existing instances may be replaced to match the new purchasing options that you specified in the policy. For example, if the group currently has 100% On-Demand capacity and the policy specifies 50% Spot capacity, this means that half of your instances will be gradually terminated and relaunched as Spot Instances. When replacing instances, Amazon EC2 Auto Scaling launches new instances before terminating the old ones, so that updating your group does not compromise the performance or availability of your application. Note the following about changing DesiredCapacity, MaxSize, or MinSize: If a scale-in activity occurs as a result of a new DesiredCapacity value that is lower than the current size of the group, the Auto Scaling group uses its termination policy to determine which instances to terminate. If you specify a new value for MinSize without specifying a value for DesiredCapacity, and the new MinSize is larger than the current size of the group, this sets the group's DesiredCapacity to the new MinSize value. If you specify a new value for MaxSize without specifying a value for DesiredCapacity, and the new MaxSize is smaller than the current size of the group, this sets the group's DesiredCapacity to the new MaxSize value. To see which properties have been set, call the DescribeAutoScalingGroups API. To view the scaling policies for an Auto Scaling group, call the DescribePolicies API. If the group has scaling policies, you can update them by calling the PutScalingPolicy API.