AWS::AutoScaling::LifecycleHook - Amazon CloudFormation
SyntaxPropertiesReturn valuesExamplesSee also
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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