在AWS中缩小Auto Scaling组会导致永久警报

Question

我目前正在使用两个扩展策略,这些策略附加到我的自动缩放组:A

1. 在调用CloudWatch警报时调用的向上扩展策略.此CloudWatch警报使用CPUUtilization指标,并在CPU上触发超过80%.
2. 另一种是缩小策略,在调用其他CloudWatch警报时调用该策略.此CloudWatch警报使用CPUUtilization指标,并在CPU低于50%时触发.

这种方法的副作用是当我的ASG实例空闲(完全按比例缩小,没有处理发生)时,我的ASG处于警报状态.

有没有办法以不同的方式设置它,以便我的ASG不处于持续警报状态？

以下是我的CloudFormation模板中的一部分警报:

"ScaleUpPolicy" : {
  "Type" : "AWS::AutoScaling::ScalingPolicy",
  "Properties" : {
    "AdjustmentType" : "ChangeInCapacity",
    "AutoScalingGroupName" : { "Ref" : "WebApplicationASG" },
    "Cooldown" : "1",
    "ScalingAdjustment" : "1"
  }
},
"CPUAlarmHigh": {
  "Type": "AWS::CloudWatch::Alarm",
  "Properties": {
    "EvaluationPeriods": "1",
    "Statistic": "Average",
    "Threshold": "80",
    "AlarmDescription": "Alarm if CPU too high or metric disappears indicating instance is down",
    "Period": "60",
    "AlarmActions": [ { "Ref": "ScaleUpPolicy" } ],
    "Namespace": "AWS/EC2",
    "Dimensions": [ {
      "Name": "AutoScalingGroupName",
      "Value": { "Ref": "WebApplicationASG" }
    } ],
    "ComparisonOperator": "GreaterThanThreshold",
    "MetricName": "CPUUtilization"
  }
},
"ScaleDownPolicy" : {
  "Type" : "AWS::AutoScaling::ScalingPolicy",
  "Properties" : {
    "AdjustmentType" : "ChangeInCapacity",
    "AutoScalingGroupName" : { "Ref" : "WebApplicationASG" },
    "Cooldown" : "1",
    "ScalingAdjustment" : "-1"
  }
},
"CPUAlarmLow": {
  "Type": "AWS::CloudWatch::Alarm",
  "Properties": {
    "EvaluationPeriods": "1",
    "Statistic": "Average",
    "Threshold": "50",
    "AlarmDescription": "Alarm if CPU is low, causing scale down",
    "Period": "60",
    "AlarmActions": [ { "Ref": "ScaleDownPolicy" } ],
    "Namespace": "AWS/EC2",
    "Dimensions": [ {
      "Name": "AutoScalingGroupName",
      "Value": { "Ref": "WebApplicationASG" }
    } ],
    "ComparisonOperator": "LessThanThreshold",
    "MetricName": "CPUUtilization"
  }
},

Answer 1

这是正常的和预期的行为。

将指标设置为警报状态不是问题-请记住，触发事件的警报状态的变化是。因此，大概是一旦您的按比例放大触发器进入警报状态，按比例缩小便会退出警报状态。然后，当指标下降时，它将返回到警报状态，并触发缩减事件。

Answer 2

您可以通过单击“隐藏自动缩放警报”复选框在控制台中隐藏这些警报。

https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/hide-autoscaling-alarms.html

仍然不理想，但总比没有好。