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AWS::AutoScaling::AutoScalingGroup

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

Auto Scaling

  • 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

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