Amazon EC2 Auto Scaling
API Reference (API Version 2011-01-01)

UpdateAutoScalingGroup

Updates the configuration for the specified Auto Scaling group.

To update an Auto Scaling group, specify the name of the group and the parameter that you want to change. Any parameters 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. Scaling activities that are currently in progress aren't affected.

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 event 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 parameters have been set, use DescribeAutoScalingGroups. You can also view the scaling policies for an Auto Scaling group using DescribePolicies. If the group has scaling policies, you can update them using PutScalingPolicy.

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

AutoScalingGroupName

The name of the Auto Scaling group.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 1600.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: Yes

AvailabilityZones.member.N

One or more Availability Zones for the group.

Type: Array of strings

Array Members: Minimum number of 1 item.

Length Constraints: Minimum length of 1. Maximum length of 255.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

DefaultCooldown

The amount of time, in seconds, after a scaling activity completes before another scaling activity can start. The default value is 300. This cooldown period is not used when a scaling-specific cooldown is specified.

Cooldown periods are not supported for target tracking scaling policies, step scaling policies, or scheduled scaling. For more information, see Scaling Cooldowns in the Amazon EC2 Auto Scaling User Guide.

Type: Integer

Required: No

DesiredCapacity

The number of EC2 instances that should be running in the Auto Scaling group. This number must be greater than or equal to the minimum size of the group and less than or equal to the maximum size of the group.

Type: Integer

Required: No

HealthCheckGracePeriod

The amount of time, in seconds, that Amazon EC2 Auto Scaling waits before checking the health status of an EC2 instance that has come into service. The default value is 0.

For more information, see Health Check Grace Period in the Amazon EC2 Auto Scaling User Guide.

Conditional: This parameter is required if you are adding an ELB health check.

Type: Integer

Required: No

HealthCheckType

The service to use for the health checks. The valid values are EC2 and ELB. If you configure an Auto Scaling group to use ELB health checks, it considers the instance unhealthy if it fails either the EC2 status checks or the load balancer health checks.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 32.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

LaunchConfigurationName

The name of the launch configuration. If you specify LaunchConfigurationName in your update request, you can't specify LaunchTemplate or MixedInstancesPolicy.

Important

To update an Auto Scaling group with a launch configuration with InstanceMonitoring set to false, you must first disable the collection of group metrics. Otherwise, you get an error. If you have previously enabled the collection of group metrics, you can disable it using DisableMetricsCollection.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 1600.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

LaunchTemplate

The launch template and version to use to specify the updates. If you specify LaunchTemplate in your update request, you can't specify LaunchConfigurationName or MixedInstancesPolicy.

Type: LaunchTemplateSpecification object

Required: No

MaxSize

The maximum size of the Auto Scaling group.

Type: Integer

Required: No

MinSize

The minimum size of the Auto Scaling group.

Type: Integer

Required: No

MixedInstancesPolicy

An embedded object that specifies a mixed instances policy.

In your call to UpdateAutoScalingGroup, you can make changes to the policy that is specified. All optional parameters are left unchanged if not specified.

For more information, see Auto Scaling Groups with Multiple Instance Types and Purchase Options in the Amazon EC2 Auto Scaling User Guide.

Type: MixedInstancesPolicy object

Required: No

NewInstancesProtectedFromScaleIn

Indicates whether newly launched instances are protected from termination by Amazon EC2 Auto Scaling when scaling in.

For more information about preventing instances from terminating on scale in, see Instance Protection in the Amazon EC2 Auto Scaling User Guide.

Type: Boolean

Required: No

PlacementGroup

The name of the placement group into which to launch your instances, if any. A placement group is a logical grouping of instances within a single Availability Zone. You cannot specify multiple Availability Zones and a placement group. For more information, see Placement Groups in the Amazon EC2 User Guide for Linux Instances.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 255.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

ServiceLinkedRoleARN

The Amazon Resource Name (ARN) of the service-linked role that the Auto Scaling group uses to call other AWS services on your behalf. For more information, see Service-Linked Roles in the Amazon EC2 Auto Scaling User Guide.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 1600.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

TerminationPolicies.member.N

A standalone termination policy or a list of termination policies used to select the instance to terminate. The policies are executed in the order that they are listed.

For more information, see Controlling Which Instances Auto Scaling Terminates During Scale In in the Amazon EC2 Auto Scaling User Guide.

Type: Array of strings

Length Constraints: Minimum length of 1. Maximum length of 1600.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

VPCZoneIdentifier

A comma-separated list of subnet IDs for virtual private cloud (VPC).

If you specify VPCZoneIdentifier with AvailabilityZones, the subnets that you specify for this parameter must reside in those Availability Zones.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2047.

Pattern: [\u0020-\uD7FF\uE000-\uFFFD\uD800\uDC00-\uDBFF\uDFFF\r\n\t]*

Required: No

Errors

For information about the errors that are common to all actions, see Common Errors.

ResourceContention

You already have a pending update to an Amazon EC2 Auto Scaling resource (for example, an Auto Scaling group, instance, or load balancer).

HTTP Status Code: 500

ScalingActivityInProgress

The operation can't be performed because there are scaling activities in progress.

HTTP Status Code: 400

ServiceLinkedRoleFailure

The service-linked role is not yet ready for use.

HTTP Status Code: 500

Examples

Example 1: Update an existing Auto Scaling group with an Elastic Load Balancing health check

Sample Request

https://autoscaling.amazonaws.com/?Action=UpdateAutoScalingGroup &HealthCheckType=ELB &HealthCheckGracePeriod=300 &AutoScalingGroupName=my-asg &Version=2011-01-01 &AUTHPARAMS

Example 2: Update an existing Auto Scaling group with a new Availability Zone

Sample Request

https://autoscaling.amazonaws.com/?Action=UpdateAutoScalingGroup &AutoScalingGroupName=my-asg-lbs &AvailabilityZones.member.1=us-east-1a &AvailabilityZones.member.2=us-east-1b &AvailabilityZones.member.3=us-east-1c &MinSize=3 &Version=2011-01-01 &AUTHPARAMS

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: