AWS::AutoScaling::AutoScalingGroup
The AWS::AutoScaling::AutoScalingGroup
resource defines an Amazon EC2 Auto
Scaling group, which is a collection of Amazon EC2 instances that are treated as a logical
grouping for the purposes of automatic scaling and management.
For more information about Amazon EC2 Auto Scaling, see the Amazon EC2 Auto Scaling User Guide.
Note
Amazon EC2 Auto Scaling configures instances launched as part of an Auto Scaling group using either a launch template or a launch configuration. We strongly recommend that you do not use launch configurations. For more information, see Launch configurations in the Amazon EC2 Auto Scaling User Guide.
For help migrating from launch configurations to launch templates, see Migrate AWS CloudFormation stacks from launch configurations to launch templates in the Amazon EC2 Auto Scaling User Guide.
Syntax
To declare this entity in your AWS CloudFormation template, use the following syntax:
JSON
{ "Type" : "AWS::AutoScaling::AutoScalingGroup", "Properties" : { "AutoScalingGroupName" :
String
, "AvailabilityZones" :[ String, ... ]
, "CapacityRebalance" :Boolean
, "Context" :String
, "Cooldown" :String
, "DefaultInstanceWarmup" :Integer
, "DesiredCapacity" :String
, "DesiredCapacityType" :String
, "HealthCheckGracePeriod" :Integer
, "HealthCheckType" :String
, "InstanceId" :String
, "InstanceMaintenancePolicy" :InstanceMaintenancePolicy
, "LaunchConfigurationName" :String
, "LaunchTemplate" :LaunchTemplateSpecification
, "LifecycleHookSpecificationList" :[ LifecycleHookSpecification, ... ]
, "LoadBalancerNames" :[ String, ... ]
, "MaxInstanceLifetime" :Integer
, "MaxSize" :String
, "MetricsCollection" :[ MetricsCollection, ... ]
, "MinSize" :String
, "MixedInstancesPolicy" :MixedInstancesPolicy
, "NewInstancesProtectedFromScaleIn" :Boolean
, "NotificationConfigurations" :[ NotificationConfiguration, ... ]
, "PlacementGroup" :String
, "ServiceLinkedRoleARN" :String
, "Tags" :[ TagProperty, ... ]
, "TargetGroupARNs" :[ String, ... ]
, "TerminationPolicies" :[ String, ... ]
, "VPCZoneIdentifier" :[ String, ... ]
} }
YAML
Type: AWS::AutoScaling::AutoScalingGroup Properties: AutoScalingGroupName:
String
AvailabilityZones:- String
CapacityRebalance:Boolean
Context:String
Cooldown:String
DefaultInstanceWarmup:Integer
DesiredCapacity:String
DesiredCapacityType:String
HealthCheckGracePeriod:Integer
HealthCheckType:String
InstanceId:String
InstanceMaintenancePolicy:InstanceMaintenancePolicy
LaunchConfigurationName:String
LaunchTemplate:LaunchTemplateSpecification
LifecycleHookSpecificationList:- LifecycleHookSpecification
LoadBalancerNames:- String
MaxInstanceLifetime:Integer
MaxSize:String
MetricsCollection:- MetricsCollection
MinSize:String
MixedInstancesPolicy:MixedInstancesPolicy
NewInstancesProtectedFromScaleIn:Boolean
NotificationConfigurations:- NotificationConfiguration
PlacementGroup:String
ServiceLinkedRoleARN:String
Tags:- TagProperty
TargetGroupARNs:- String
TerminationPolicies:- String
VPCZoneIdentifier:- String
Properties
AutoScalingGroupName
-
The name of the Auto Scaling group. This name must be unique per Region per account.
The name can contain any ASCII character 33 to 126 including most punctuation characters, digits, and upper and lowercased letters.
Note
You cannot use a colon (:) in the name.
Required: No
Type: String
Update requires: Replacement
AvailabilityZones
-
A list of Availability Zones where instances in the Auto Scaling group can be created. Used for launching into the default VPC subnet in each Availability Zone when not using the
VPCZoneIdentifier
property, or for attaching a network interface when an existing network interface ID is specified in a launch template.Required: No
Type: Array of String
Update requires: No interruption
CapacityRebalance
-
Indicates whether Capacity Rebalancing is enabled. Otherwise, Capacity Rebalancing is disabled. When you turn on Capacity Rebalancing, Amazon EC2 Auto Scaling attempts to launch a Spot Instance whenever Amazon EC2 notifies that a Spot Instance is at an elevated risk of interruption. After launching a new instance, it then terminates an old instance. For more information, see Use Capacity Rebalancing to handle Amazon EC2 Spot Interruptions in the in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: Boolean
Update requires: No interruption
Context
-
Reserved.
Required: No
Type: String
Update requires: No interruption
Cooldown
-
Only needed if you use simple scaling policies.
The amount of time, in seconds, between one scaling activity ending and another one starting due to simple scaling policies. For more information, see Scaling cooldowns for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide.
Default:
300
secondsRequired: No
Type: String
Update requires: No interruption
DefaultInstanceWarmup
-
The amount of time, in seconds, until a new instance is considered to have finished initializing and resource consumption to become stable after it enters the
InService
state.During an instance refresh, Amazon EC2 Auto Scaling waits for the warm-up period after it replaces an instance before it moves on to replacing the next instance. Amazon EC2 Auto Scaling also waits for the warm-up period before aggregating the metrics for new instances with existing instances in the Amazon CloudWatch metrics that are used for scaling, resulting in more reliable usage data. For more information, see Set the default instance warmup for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.
Important
To manage various warm-up settings at the group level, we recommend that you set the default instance warmup, even if it is set to 0 seconds. To remove a value that you previously set, include the property but specify
-1
for the value. However, we strongly recommend keeping the default instance warmup enabled by specifying a value of0
or other nominal value.Default: None
Required: No
Type: Integer
Update requires: No interruption
DesiredCapacity
-
The desired capacity is the initial capacity of the Auto Scaling group at the time of its creation and the capacity it attempts to maintain. It can scale beyond this capacity if you configure automatic scaling.
The 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. If you do not specify a desired capacity when creating the stack, the default is the minimum size of the group.
CloudFormation marks the Auto Scaling group as successful (by setting its status to CREATE_COMPLETE) when the desired capacity is reached. However, if a maximum Spot price is set in the launch template or launch configuration that you specified, then desired capacity is not used as a criteria for success. Whether your request is fulfilled depends on Spot Instance capacity and your maximum price.
Required: No
Type: String
Pattern:
^[0-9]+$
Update requires: No interruption
DesiredCapacityType
-
The unit of measurement for the value specified for desired capacity. Amazon EC2 Auto Scaling supports
DesiredCapacityType
for attribute-based instance type selection only. For more information, see Create a mixed instances group using attribute-based instance type selection in the Amazon EC2 Auto Scaling User Guide.By default, Amazon EC2 Auto Scaling specifies
units
, which translates into number of instances.Valid values:
units
|vcpu
|memory-mib
Required: No
Type: String
Update requires: No interruption
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 and marking it unhealthy due to a failed health check. This is useful if your instances do not immediately pass their health checks after they enter the
InService
state. For more information, see Set the health check grace period for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.Default:
0
secondsRequired: No
Type: Integer
Update requires: No interruption
HealthCheckType
-
A comma-separated value string of one or more health check types.
The valid values are
EC2
,EBS
,ELB
, andVPC_LATTICE
.EC2
is the default health check and cannot be disabled. For more information, see Health checks for instances in an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.Only specify
EC2
if you must clear a value that was previously set.Required: No
Type: String
Update requires: No interruption
InstanceId
-
The ID of the instance used to base the launch configuration on. For more information, see Create an Auto Scaling group using an EC2 instance in the Amazon EC2 Auto Scaling User Guide.
If you specify
LaunchTemplate
,MixedInstancesPolicy
, orLaunchConfigurationName
, don't specifyInstanceId
.Required: No
Type: String
Update requires: Replacement
InstanceMaintenancePolicy
-
An instance maintenance policy. For more information, see Set instance maintenance policy in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: InstanceMaintenancePolicy
Update requires: No interruption
LaunchConfigurationName
-
The name of the launch configuration to use to launch instances.
Required only if you don't specify
LaunchTemplate
,MixedInstancesPolicy
, orInstanceId
.Required: No
Type: String
Update requires: Some interruptions
LaunchTemplate
-
Information used to specify the launch template and version to use to launch instances. You can alternatively associate a launch template to the Auto Scaling group by specifying a
MixedInstancesPolicy
. For more information about creating launch templates, see Create a launch template for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.If you omit this property, you must specify
MixedInstancesPolicy
,LaunchConfigurationName
, orInstanceId
.Required: No
Type: LaunchTemplateSpecification
Update requires: Some interruptions
LifecycleHookSpecificationList
-
One or more lifecycle hooks to add to the Auto Scaling group before instances are launched.
Required: No
Type: Array of LifecycleHookSpecification
Update requires: No interruption
LoadBalancerNames
-
A list of Classic Load Balancers associated with this Auto Scaling group. For Application Load Balancers, Network Load Balancers, and Gateway Load Balancers, specify the
TargetGroupARNs
property instead.Required: No
Type: Array of String
Update requires: No interruption
MaxInstanceLifetime
-
The maximum amount of time, in seconds, that an instance can be in service. The default is null. If specified, the value must be either 0 or a number equal to or greater than 86,400 seconds (1 day). For more information, see Replace Auto Scaling instances based on maximum instance lifetime in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: Integer
Update requires: No interruption
MaxSize
-
The maximum size of the group.
Note
With a mixed instances policy that uses instance weighting, Amazon EC2 Auto Scaling may need to go above
MaxSize
to meet your capacity requirements. In this event, Amazon EC2 Auto Scaling will never go aboveMaxSize
by more than your largest instance weight (weights that define how many units each instance contributes to the desired capacity of the group).Required: Yes
Type: String
Pattern:
^[0-9]+$
Update requires: No interruption
MetricsCollection
-
Enables the monitoring of group metrics of an Auto Scaling group. By default, these metrics are disabled.
Required: No
Type: Array of MetricsCollection
Update requires: No interruption
MinSize
-
The minimum size of the group.
Required: Yes
Type: String
Pattern:
^[0-9]+$
Update requires: No interruption
MixedInstancesPolicy
-
An embedded object that specifies a mixed instances policy.
The policy includes properties that not only define the distribution of On-Demand Instances and Spot Instances, the maximum price to pay for Spot Instances (optional), and how the Auto Scaling group allocates instance types to fulfill On-Demand and Spot capacities, but also the properties that specify the instance configuration information—the launch template and instance types. The policy can also include a weight for each instance type and different launch templates for individual instance types.
For more information, see Auto Scaling groups with multiple instance types and purchase options in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: MixedInstancesPolicy
Update requires: Some interruptions
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 Use instance scale-in protection in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: Boolean
Update requires: No interruption
NotificationConfigurations
-
Configures an Auto Scaling group to send notifications when specified events take place.
Required: No
Type: Array of NotificationConfiguration
Update requires: No interruption
PlacementGroup
-
The name of the placement group into which to launch your instances. For more information, see Placement groups in the Amazon EC2 User Guide for Linux Instances.
Note
A cluster placement group is a logical grouping of instances within a single Availability Zone. You cannot specify multiple Availability Zones and a cluster placement group.
Required: No
Type: String
Update requires: Some interruptions
ServiceLinkedRoleARN
-
The Amazon Resource Name (ARN) of the service-linked role that the Auto Scaling group uses to call other AWS service on your behalf. By default, Amazon EC2 Auto Scaling uses a service-linked role named
AWSServiceRoleForAutoScaling
, which it creates if it does not exist. For more information, see Service-linked roles in the Amazon EC2 Auto Scaling User Guide.Required: No
Type: String
Update requires: No interruption
-
One or more tags. You can tag your Auto Scaling group and propagate the tags to the Amazon EC2 instances it launches. Tags are not propagated to Amazon EBS volumes. To add tags to Amazon EBS volumes, specify the tags in a launch template but use caution. If the launch template specifies an instance tag with a key that is also specified for the Auto Scaling group, Amazon EC2 Auto Scaling overrides the value of that instance tag with the value specified by the Auto Scaling group. For more information, see Tag Auto Scaling groups and instances in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: Array of TagProperty
Update requires: No interruption
TargetGroupARNs
-
The Amazon Resource Names (ARN) of the Elastic Load Balancing target groups to associate with the Auto Scaling group. Instances are registered as targets with the target groups. The target groups receive incoming traffic and route requests to one or more registered targets. For more information, see Use Elastic Load Balancing to distribute traffic across the instances in your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.
Required: No
Type: Array of String
Update requires: No interruption
TerminationPolicies
-
A policy or a list of policies that are used to select the instance to terminate. These policies are executed in the order that you list them. For more information, see Configure termination policies for Amazon EC2 Auto Scaling in the Amazon EC2 Auto Scaling User Guide.
Valid values:
Default
|AllocationStrategy
|ClosestToNextInstanceHour
|NewestInstance
|OldestInstance
|OldestLaunchConfiguration
|OldestLaunchTemplate
|arn:aws:lambda:region:account-id:function:my-function:my-alias
Required: No
Type: Array of String
Update requires: No interruption
VPCZoneIdentifier
-
A list of subnet IDs for a virtual private cloud (VPC) where instances in the Auto Scaling group can be created.
If this resource specifies public subnets and is also in a VPC that is defined in the same stack template, you must use the DependsOn attribute to declare a dependency on the VPC-gateway attachment.
Note
When you update
VPCZoneIdentifier
, this retains the same Auto Scaling group and replaces old instances with new ones, according to the specified subnets. You can optionally specify how CloudFormation handles these updates by using an UpdatePolicy attribute.Required to launch instances into a nondefault VPC. If you specify
VPCZoneIdentifier
withAvailabilityZones
, the subnets that you specify for this property must reside in those Availability Zones.Required: Conditional
Type: Array of String
Update requires: Some interruptions
Return values
Ref
When you pass the logical ID of this resource to the intrinsic Ref
function, Ref
returns the resource name. For example:
mystack-myasgroup-NT5EUXTNTXXD
.
For more information about using the Ref
function, see Ref
.
Remarks
When you update the launch template or launch configuration for an Auto Scaling group, this update action does not deploy any change across the running Amazon EC2 instances in the Auto Scaling group. All new instances will get the updated configuration, but existing instances continue to run with the configuration that they were originally launched with. This works the same way as any other Auto Scaling group.
You can add an UpdatePolicy attribute to your stack to perform rolling updates (or replace the group) when a change has been made to the group. You can find a sample update policy for rolling updates in Configure Amazon EC2 Auto Scaling resources. Alternatively, you can force a rolling update on your instances at any time after updating the stack by starting an instance refresh. For more information, see Replace Auto Scaling instances based on an instance refresh in the Amazon EC2 Auto Scaling User Guide.
You can use a CreationPolicy
attribute with an Auto Scaling group to prevent its status from reaching create
complete until CloudFormation receives a specified number of success signals. For more
information, see Use a
CreationPolicy to Wait for On-Instance Configurations
Note that Amazon EC2 Auto Scaling provides scaling activities to help you monitor the progress of your Auto Scaling group and to assist in troubleshooting any configuration issues when launching Amazon EC2 instances. For more information, see Verify a scaling activity for an Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.
Examples
The following examples create or make changes to an Auto Scaling group.
An Auto Scaling group and a launch template with a parameters section
The following example shows an Auto Scaling group. You specify values for the
MaxSize
and MinSize
properties.
It also shows an AWS::EC2::LaunchTemplate resource that contains the instance configuration
information for the group, which uses the LaunchTemplate
property to specify
the launch template. The Ref intrinsic function gets the ID of the AWS::EC2::LaunchTemplate
resource myLaunchTemplate
. The GetAtt function gets the latest version number (for example, 1
) of
the launch template for the Version
property.
This example references parameters to specify the ImageId
and InstanceType
properties for the launch template and the VPCZoneIdentifier
property for the
group. Parameters are variables that you can specify when you create or update the stack.
By default, the ImageId
property of the launch template references the latest
Amazon Linux 2 AMI from the AWS Systems Manager Parameter Store. For more
information, see AWS Systems Manager Parameter Store in the
AWS Systems Manager User Guide and the blog post Query for the latest Amazon Linux AMI IDs using AWS Systems Manager
Parameter Store
JSON
{ "AWSTemplateFormatVersion": "2010-09-09", "Parameters": { "LatestAmiId": { "Description": "Region specific image from the Parameter Store", "Type": "AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>", "Default": "/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2" }, "InstanceType": { "Description": "Amazon EC2 instance type for the instances", "Type": "String", "AllowedValues": [ "t3.micro", "t3.small", "t3.medium" ], "Default": "t3.micro" }, "Subnets": { "Type": "List<AWS::EC2::Subnet::Id>", "Description": "A list of subnets for the Auto Scaling group" } }, "Resources": { "myLaunchTemplate": { "Type": "AWS::EC2::LaunchTemplate", "Properties": { "LaunchTemplateName": { "Fn::Sub": "${AWS::StackName}-launch-template" }, "LaunchTemplateData": { "ImageId": { "Ref": "LatestAmiId" }, "InstanceType": { "Ref": "InstanceType" } } } }, "myASG": { "Type": "AWS::AutoScaling::AutoScalingGroup", "Properties": { "LaunchTemplate": { "LaunchTemplateId": { "Ref": "myLaunchTemplate" }, "Version": { "Fn::GetAtt": [ "myLaunchTemplate", "LatestVersionNumber" ] } }, "MaxSize": "1", "MinSize": "1", "VPCZoneIdentifier": { "Ref": "Subnets" } } } } }
YAML
AWSTemplateFormatVersion: '2010-09-09' Parameters: LatestAmiId: Description: Region specific image from the Parameter Store Type: 'AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>' Default: '/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2' InstanceType: Description: Amazon EC2 instance type for the instances Type: String AllowedValues: - t3.micro - t3.small - t3.medium Default: t3.micro Subnets: Type: 'List<AWS::EC2::Subnet::Id>' Description: A list of subnets for the Auto Scaling group Resources: myLaunchTemplate: Type: AWS::EC2::LaunchTemplate Properties: LaunchTemplateName: !Sub ${AWS::StackName}-launch-template LaunchTemplateData: ImageId: !Ref LatestAmiId InstanceType: !Ref InstanceType myASG: Type: AWS::AutoScaling::AutoScalingGroup Properties: LaunchTemplate: LaunchTemplateId: !Ref myLaunchTemplate Version: !GetAtt myLaunchTemplate.LatestVersionNumber MaxSize: '1' MinSize: '1' VPCZoneIdentifier: !Ref Subnets
Auto Scaling group with CloudWatch monitoring enabled and custom tags
The following snippet shows an Auto Scaling group with CloudWatch monitoring enabled
and custom tags. The LaunchTemplate
property references an AWS::EC2::LaunchTemplate resource with the logical name
myLaunchTemplate
that is defined elsewhere in your template.
You specify the CloudWatch metrics to monitor using the MetricsCollection
property. If you keep the metrics as they are, only GroupMinSize
and
GroupMaxSize
metrics are enabled.
You specify the tag keys and tag key values for the Tags
property. If you
keep the provided tags, the first tag, Environment
=Production
,
is assigned to the Auto Scaling group and to any EC2 instances launched as part of the
Auto Scaling group. The second tag, Purpose
=WebServerGroup
, is
assigned only to the Auto Scaling group itself.
You also specify values for the MaxSize
, MinSize
, and
VPCZoneIdentifier
properties.
JSON
{ "Resources": { "myASG": { "Type": "AWS::AutoScaling::AutoScalingGroup", "Properties": { "LaunchTemplate": { "LaunchTemplateId": { "Ref": "myLaunchTemplate" }, "Version": { "Fn::GetAtt": [ "myLaunchTemplate", "LatestVersionNumber" ] } }, "MaxSize": "1", "MinSize": "1", "VPCZoneIdentifier": [ "subnetIdAz1", "subnetIdAz2", "subnetIdAz3" ], "MetricsCollection": [ { "Granularity": "1Minute", "Metrics": [ "GroupMinSize", "GroupMaxSize" ] } ], "Tags": [ { "Key": "Environment", "Value": "Production", "PropagateAtLaunch": "true" }, { "Key": "Purpose", "Value": "WebServerGroup", "PropagateAtLaunch": "false" } ] } } } }
YAML
--- Resources: myASG: Type: AWS::AutoScaling::AutoScalingGroup Properties: LaunchTemplate: LaunchTemplateId: !Ref myLaunchTemplate Version: !GetAtt myLaunchTemplate.LatestVersionNumber MaxSize: '1' MinSize: '1' VPCZoneIdentifier: - subnetIdAz1 - subnetIdAz2 - subnetIdAz3 MetricsCollection: - Granularity: 1Minute Metrics: - GroupMinSize - GroupMaxSize Tags: - Key: Environment Value: Production PropagateAtLaunch: true - Key: Purpose Value: WebServerGroup PropagateAtLaunch: false
See also
-
You can find additional useful snippets in the following sections of the AWS CloudFormation User Guide:
-
For examples of Auto Scaling groups, see Configure Amazon EC2 Auto Scaling resources.
-
For examples of launch templates, see Create launch templates.
-
-
Migrate AWS CloudFormation stacks from launch configurations to launch templates in the Amazon EC2 Auto Scaling User Guide
-
CreateAutoScalingGroup and UpdateAutoScalingGroup in the Amazon EC2 Auto Scaling API Reference