AWS::AutoScaling::LifecycleHook - Amazon CloudFormation
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AWS::AutoScaling::LifecycleHook

The AWS::AutoScaling::LifecycleHook resource specifies lifecycle hooks for an Auto Scaling group. These 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. A lifecycle hook provides a specified amount of time (one hour by default) to wait for the action to complete before the instance transitions to the next state.

Use lifecycle hooks to prepare new instances for use or to delay them from being registered behind a load balancer before their configuration has been applied completely. You can also use lifecycle hooks to prepare running instances to be terminated by, for example, downloading logs or other data.

For more information, see Amazon EC2 Auto Scaling lifecycle hooks in the Amazon EC2 Auto Scaling User Guide.

Syntax

To declare this entity in your Amazon CloudFormation template, use the following syntax:

JSON

{ "Type" : "AWS::AutoScaling::LifecycleHook", "Properties" : { "AutoScalingGroupName" : String, "DefaultResult" : String, "HeartbeatTimeout" : Integer, "LifecycleHookName" : String, "LifecycleTransition" : String, "NotificationMetadata" : String, "NotificationTargetARN" : String, "RoleARN" : String } }

YAML

Type: AWS::AutoScaling::LifecycleHook Properties: AutoScalingGroupName: String DefaultResult: String HeartbeatTimeout: Integer LifecycleHookName: String LifecycleTransition: String NotificationMetadata: String NotificationTargetARN: String RoleARN: String

Properties

AutoScalingGroupName

The name of the Auto Scaling group.

Required: Yes

Type: String

Update requires: Replacement

DefaultResult

The action the Auto Scaling group takes when the lifecycle hook timeout elapses or if an unexpected failure occurs. The default value is ABANDON.

Valid values: CONTINUE | ABANDON

Required: No

Type: String

Update requires: No interruption

HeartbeatTimeout

The maximum time, in seconds, that can elapse before the lifecycle hook times out. The range is from 30 to 7200 seconds. The default value is 3600 seconds (1 hour).

Required: No

Type: Integer

Update requires: No interruption

LifecycleHookName

The name of the lifecycle hook.

Required: No

Type: String

Minimum: 1

Maximum: 255

Update requires: Replacement

LifecycleTransition

The lifecycle transition. For Auto Scaling groups, there are two major lifecycle transitions.

  • To create a lifecycle hook for scale-out events, specify autoscaling:EC2_INSTANCE_LAUNCHING.

  • To create a lifecycle hook for scale-in events, specify autoscaling:EC2_INSTANCE_TERMINATING.

Required: Yes

Type: String

Update requires: No interruption

NotificationMetadata

Additional information that you want to include any time Amazon EC2 Auto Scaling sends a message to the notification target.

Required: No

Type: String

Minimum: 1

Maximum: 1023

Update requires: No interruption

NotificationTargetARN

The Amazon Resource Name (ARN) of the notification target that Amazon EC2 Auto Scaling sends notifications to when an instance is in a wait state for the lifecycle hook. You can specify an Amazon SNS topic or an Amazon SQS queue.

Required: No

Type: String

Update requires: No interruption

RoleARN

The ARN of the IAM role that allows the Auto Scaling group to publish to the specified notification target. For information about creating this role, see Prepare to add a lifecycle hook to your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

Valid only if the notification target is an Amazon SNS topic or an Amazon SQS queue.

Required: No

Type: String

Update requires: No interruption

Return values

Ref

When you pass the logical ID of this resource to the intrinsic Ref function, Ref returns the resource name. For example: mylifecyclehook.

For more information about using the Ref function, see Ref.

Examples

The following examples specify lifecycle hooks.

For other examples of lifecycle hooks, see our GitHub repository. Included are examples of lifecycle hooks that work with warm pools.

Lifecycle hook for instance launch

The following example creates a launch template, an Auto Scaling group, and a lifecycle hook that supports a custom action on your instances at launch. When you create a launch template, you can include user data to perform configuration tasks and run scripts when an instance launches. By doing so, you do not need to configure a notification target. In this example, the hook keeps each instance in a wait state for 60 seconds to give the user data script time to complete before the instance enters the InService state.

The example bash script in the user data customizes the hostname on instances to include the launch template name and the instance ID. The script gets the ID of the instance from the instance metadata. For more information, see Retrieve instance metadata in the Amazon EC2 User Guide for Linux Instances.

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": "CommaDelimitedList" } }, "Resources": { "myAppLaunchTemplate": { "Type": "AWS::EC2::LaunchTemplate", "Properties": { "LaunchTemplateName": { "Fn::Sub": "${AWS::StackName}-launch-template" }, "LaunchTemplateData": { "ImageId": { "Ref": "LatestAmiId" }, "InstanceType": { "Ref": "InstanceType" }, "KeyName": "MyKeyPair", "SecurityGroupIds": [ "sg-083cd3bfb8example" ], "UserData": {"Fn::Base64": {"Fn::Join": [ "", [ "#!/usr/bin/env bash\n", "set -e\n", "export INSTANCE_ID=$(curl -sLf http://169.254.169.254/latest/meta-data/instance-id)", "\n", "export NEW_HOSTNAME=\"${LaunchTemplateName}-$INSTANCE_ID\"", "\n", "hostname $NEW_HOSTNAME", "\n" ]]}} } } }, "myASG": { "Type": "AWS::AutoScaling::AutoScalingGroup", "Properties": { "LaunchTemplate": { "LaunchTemplateId": { "Ref": "myAppLaunchTemplate" }, "Version": { "Fn::GetAtt": [ "myAppLaunchTemplate", "DefaultVersionNumber" ] } }, "MaxSize": 10, "MinSize": 1, "VPCZoneIdentifier": { "Ref": "Subnets" }, "LifecycleHookSpecificationList": [ { "LifecycleTransition": "autoscaling:EC2_INSTANCE_LAUNCHING", "LifecycleHookName": "myLaunchLifecycleHook", "DefaultResult": "CONTINUE", "HeartbeatTimeout": 60 } ] } } } }

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: CommaDelimitedList Resources: myAppLaunchTemplate: Type: AWS::EC2::LaunchTemplate Properties: LaunchTemplateName: !Sub ${AWS::StackName}-launch-template LaunchTemplateData: ImageId: !Ref LatestAmiId InstanceType: !Ref InstanceType KeyName: MyKeyPair SecurityGroupIds: - sg-083cd3bfb8example UserData: Fn::Base64: !Sub | #!/usr/bin/env bash set -e export INSTANCE_ID=$(curl -sLf http://169.254.169.254/latest/meta-data/instance-id) export NEW_HOSTNAME="${LaunchTemplateName}-$INSTANCE_ID" hostname $NEW_HOSTNAME myASG: Type: AWS::AutoScaling::AutoScalingGroup Properties: LaunchTemplate: LaunchTemplateId: !Ref myAppLaunchTemplate Version: !GetAtt myAppLaunchTemplate.DefaultVersionNumber MaxSize: '10' MinSize: '1' VPCZoneIdentifier: !Ref Subnets LifecycleHookSpecificationList: - LifecycleTransition: autoscaling:EC2_INSTANCE_LAUNCHING LifecycleHookName: myLaunchLifecycleHook DefaultResult: CONTINUE HeartbeatTimeout: '60'

Lifecycle hook for instance termination

The following example specifies a lifecycle hook that supports a custom action at instance termination. It uses the Ref intrinsic function to refer to an Auto Scaling group (whose logical name is myASG) that is declared elsewhere in the same template. It uses the NotificationMetadata property to specify additional information to be sent with the notification, such as the name of the cluster to which the instance belongs.

This snippet does not include the notification target that would need to exist or be created to complete the configuration. For information about creating these resources, see Configure a notification target for lifecycle notifications in the Amazon EC2 Auto Scaling User Guide.

JSON

{ "myTerminationLifecycleHook":{ "Type":"AWS::AutoScaling::LifecycleHook", "Properties":{ "AutoScalingGroupName":{ "Ref":"myASG" }, "LifecycleTransition":"autoscaling:EC2_INSTANCE_TERMINATING", "HeartbeatTimeout": 300, "DefaultResult": "CONTINUE", "NotificationMetadata": "optional metadata" } } }

YAML

--- myTerminationLifecycleHook: Type: AWS::AutoScaling::LifecycleHook Properties: AutoScalingGroupName: !Ref myASG LifecycleTransition: autoscaling:EC2_INSTANCE_TERMINATING HeartbeatTimeout: '300' DefaultResult: CONTINUE NotificationMetadata: optional metadata

Lifecycle hook that specifies a notification target ARN and role ARN

The following example creates an Auto Scaling group with a lifecycle hook that supports a custom action at instance launch. This example snippet uses the NotificationTargetARN and RoleARN properties to specify the Amazon SQS queue and IAM role to use to receive notification when a lifecycle action occurs.

This snippet does not include the Amazon SQS queue and IAM role resources that would need to exist or be created to complete the configuration. For information about creating these resources, see Configure a notification target for lifecycle notifications in the Amazon EC2 Auto Scaling User Guide.

JSON

{ "AWSTemplateFormatVersion":"2010-09-09", "Parameters":{ "Subnets":{ "Type":"CommaDelimitedList" } }, "Resources":{ "myASG":{ "Type":"AWS::AutoScaling::AutoScalingGroup", "Properties":{ "MaxSize":"3", "MinSize":"1", "LaunchTemplate": { "LaunchTemplateId": { "Ref":"myLaunchTemplate" }, "Version":{ "Ref":"myLaunchTemplateVersionNumber" } }, "VPCZoneIdentifier":{ "Ref":"Subnets" }, "LifecycleHookSpecificationList":[ { "LifecycleTransition":"autoscaling:EC2_INSTANCE_LAUNCHING", "LifecycleHookName":"myLaunchLifecycleHook", "HeartbeatTimeout":4800, "NotificationTargetARN":{ "Fn::GetAtt":[ "SQS", "Arn" ] }, "RoleArn":{ "Fn::Join":[ ":", [ "arn:aws:iam:", { "Ref":"AWS::AccountId" }, "role/role-name" ] ] } } ] } }, "SQS":{ "Type":"AWS::SQS::Queue" } } }

YAML

AWSTemplateFormatVersion: 2010-09-09 Parameters: Subnets: Type: CommaDelimitedList Resources: myASG: Type: AWS::AutoScaling::AutoScalingGroup Properties: MaxSize: '3' MinSize: '1' LaunchTemplate: LaunchTemplateId: !Ref myLaunchTemplate Version: !Ref myLaunchTemplateVersionNumber VPCZoneIdentifier: !Ref Subnets LifecycleHookSpecificationList: - LifecycleTransition: autoscaling:EC2_INSTANCE_LAUNCHING LifecycleHookName: myLaunchLifecycleHook HeartbeatTimeout: '4800' NotificationTargetARN: !GetAtt SQS.Arn RoleARN: !Join - ':' - - 'arn:aws:iam:' - !Ref 'AWS::AccountId' - role/role-name SQS: Type: AWS::SQS::Queue

See also