(因为我是法律新手，所以提前道歉)
我正在使用cloudformation堆栈来管理我的ECS集群。
假设我们有一个期望容量为5个ec2实例(minSize: 1, maxSize:7)的ASG，并且我手动将期望容量的值从5更改为2，它减少了通过集群更改集的实例数量，所有实例都同时关闭。它没有时间调度左边实例上的前一个容器。因此，如果从5个实例变为2个实例，则直接关闭所有3个实例。如果不幸的是同一类型的所有容器都在这3台机器上，那么容器就不存在了，服务就会关闭。
可以设置"冷却时间"吗?每次终止之间?使用缩放策略显然没有帮助，因为我们不想设置一个度量，因为可用的度量在我的情况下没有帮助。
请在下面找到一些日志:
2021-01-15 15:45:52 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Rolling update initiated. Terminating 3 obsolete instance(s) in batches of 1, while keeping at least 1 instance(s) in service. Waiting on resource signals with a timeout of PT5M when new instances are added to the autoscaling group.
2021-01-15 15:45:52 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Temporarily setting autoscaling group MinSize and DesiredCapacity to 3.
2021-01-15 15:45:54 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Terminating instance(s) [i-X]; replacing with 1 new instance(s).
2021-01-15 15:47:40 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS New instance(s) added to autoscaling group - Waiting on 1 resource signal(s) with a timeout of PT5M.
2021-01-15 15:47:40 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Successfully terminated instance(s) [i-X] (Progress 33%).
2021-01-15 15:52:42 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Terminating instance(s) [i-X]; replacing with 1 new instance(s).
2021-01-15 15:53:59 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS New instance(s) added to autoscaling group - Waiting on 1 resource signal(s) with a timeout of PT5M.
2021-01-15 15:53:59 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Successfully terminated instance(s) [i-X] (Progress 67%).
2021-01-15 15:59:02 UTC+0100 dev-cluster UPDATE_ROLLBACK_IN_PROGRESS The following resource(s) failed to update: [autoScalingGroup].
2021-01-15 15:59:17 UTC+0100 securityGroup UPDATE_IN_PROGRESS -
2021-01-15 15:59:32 UTC+0100 securityGroup UPDATE_COMPLETE -
2021-01-15 15:59:33 UTC+0100 launchConfiguration UPDATE_COMPLETE -
2021-01-15 15:59:34 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS -
2021-01-15 15:59:37 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Rolling update initiated. Terminating 2 obsolete instance(s) in batches of 1, while keeping at least 1 instance(s) in service. Waiting on resource signals with a timeout of PT5M when new instances are added to the autoscaling group.
2021-01-15 15:59:37 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Temporarily setting autoscaling group MinSize and DesiredCapacity to 3.
2021-01-15 15:59:38 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Terminating instance(s) [i-X]; replacing with 1 new instance(s).
2021-01-15 16:01:25 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS New instance(s) added to autoscaling group - Waiting on 1 resource signal(s) with a timeout of PT5M.
2021-01-15 16:01:25 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Successfully terminated instance(s) [i-X] (Progress 50%).
2021-01-15 16:01:46 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Received SUCCESS signal with UniqueId i-X
2021-01-15 16:01:47 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Terminating instance(s) [i-X]; replacing with 1 new instance(s).
2021-01-15 16:03:34 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS New instance(s) added to autoscaling group - Waiting on 1 resource signal(s) with a timeout of PT5M.
2021-01-15 16:03:34 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Received SUCCESS signal with UniqueId i-X
2021-01-15 16:03:34 UTC+0100 autoScalingGroup UPDATE_IN_PROGRESS Successfully terminated instance(s) [i-X] (Progress 100%).
2021-01-15 16:03:37 UTC+0100 autoScalingGroup UPDATE_COMPLETE -
2021-01-15 16:03:37 UTC+0100 dev-cluster UPDATE_ROLLBACK_COMPLETE_CLEANUP_IN_PROGRESS -
2021-01-15 16:03:38 UTC+0100 launchConfiguration DELETE_IN_PROGRESS -
2021-01-15 16:03:39 UTC+0100 dev-cluster UPDATE_ROLLBACK_COMPLETE -
2021-01-15 16:03:39 UTC+0100 launchConfiguration DELETE_COMPLETE -
提前感谢您的帮助!
对于您的直接问题，没有任何功能可以强制ASG在发生所需的下降时只删除x个实例
如果你还没有，你应该在ASG上有一个生命周期钩子来触发一个脚本，告诉ECS从实例中抽出容器(我假设从上下文中你使用ECS)。但是，在这种情况下，您仍然需要每次手动降低所需的1。https://aws.amazon.com/blogs/compute/how-to-automate-container-instance-draining-in-amazon-ecs/
如果您在CloudFormation中降低了所需的值，那么您可以将UpdatePolicy附加到组上，告诉CFN执行rolllingupdate以分批替换实例，每次1个https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-updatepolicy.html
如果您正在使用ECS，设置2个目标跟踪缩放策略通常是一个好主意。CPUReservation为1,MemoryReservation为1。如果您希望强制ASG每次不扩展超过1个实例，也可以基于这些指标手动创建步骤扩展策略，但是在CFN中创建4个cloudwatch警报将是一个痛苦的过程
另一个选择是在ECS中使用CapacityProvider，它将在任何有任务运行的实例上启用实例保护