AWS::AutoScaling::AutoScalingGroup

• Auto Scaling Groups (ASG) scales instances to match the load demand
• Scale out: add instances
• Scale in: remove instances

• New instances can be automatically registered to LB
• ASG ensures to keep the desired number of replicas

• ASG terminates unhealthy instances can relaunch it

• Reasons to not terminate an unhealthy instance:

• Instance on impaired status
• Healthcheck grace period has not yet expired
• Instance has failed ELB health check

Properties

• https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-autoscaling-autoscalinggroup.html

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

LaunchTemplate

• Reference to AWS::EC2::LaunchTemplate
• LaunchTemplate can be used to provision capacity across multiple instance types (e.g., on-demand and spot instances)

LaunchConfigurationName

• Reference to AWS::AutoScaling::LaunchConfiguration
• LaunchConfiguration cannot be used to provision capacity to multiple instance types

TerminationPolicies

• Termination Policy
• Terminate instance from AZ with most instances
• Terminate instance with oldest launch configuration