ECS Fargate 自动扩展更快? [英] ECS Fargate autoscaling more rapidly?

问题描述

我正在对我的自动扩展 AWS ECS Fargate 堆栈进行负载测试，其中包括:

I'm load testing my auto scaling AWS ECS Fargate stack which comprises of:

• 具有指向 ECS 的目标组的应用程序负载均衡器 (ALB)，
• ECS 集群、服务、任务、ApplicationAutoScaling::ScalableTarget 和 ApplicationAutoScaling::ScalingPolicy，
• 应用程序自动缩放策略定义了一个目标跟踪策略:
  • 类型:TargetTrackingScaling，
  • PredefinedMetricType:ALBRequestCountPerTarget，
  • 阈值 = 1000 个请求
  • 当 1 个数据点在过去 1 分钟评估期内超过阈值时触发警报.

  这一切正常.警报确实被触发了，我看到了扩展操作的发生.但是检测阈值违规"感觉很慢.这是我的负载测试和 AWS 事件的时间安排(从 JMeter 日志和 AWS 控制台的不同位置在此处整理):

  This all works fine. The alarms do get triggered and I see the scale out actions happening. But it feels slow to detect the "threshold breach". This is the timing of my load test and AWS events (collated here from different places in the JMeter logs and the AWS console):

  10:44:32 start load test (this is the first request timestamp entry in JMeter logs)
  10:44:36 4 seconds later (in the the JMeter logs), we see that the load test reaches it's 1000th request to the ALB. At this point in time, we're above the threshold and waiting for AWS to detect that...
  10:46:10 1m34s later, I can finally see the spike show up in alarm graph on the cloudwatch alarm detail page BUT the alarm is still in OK state!
      NOTE: notice the 1m34s delay in detecting the spike, if it gets a datapoint every 60 seconds, it should be MAX 60 seconds before it detects it: my load test blasts out 1000 request every 4 seconds!!
  10:46:50 the alarm finally goes from OK to ALARM state
      NOTE: at this point, we're 2m14s past the moment when requests started pounding the server at a rate of 1000 requests every 6 seconds!
      NOTE: 3 seconds later, after the alarm finally went off, the "scale out" action gets called (awesome, that part is quick):
  14:46:53 Action Successfully executed action    arn:aws:autoscaling:us-east-1:MYACCOUNTID:scalingPolicy:51f0a780-28d5-4005-9681-84244912954d:resource/ecs/service/my-ecs-cluster/my-service:policyName/alb-requests-per-target-per-minute:createdBy/ffacb0ac-2456-4751-b9c0-b909c66e9868
  After that, I follow the actions in the ECS "events tab":
  10:46:53 Message: Successfully set desired count to 6. Waiting for change to be fulfilled by ecs. Cause: monitor alarm TargetTracking-service/my-ecs-cluster-cce/my-service-AlarmHigh-fae560cc-e2ee-4c6b-8551-9129d3b5a6d3 in state ALARM triggered policy alb-requests-per-target-per-minute
  10:47:08 service my-service has started 5 tasks: task 7e9612fa981c4936bd0f33c52cbded72 task e6cd126f265842c1b35c0186c8f9b9a6 task ba4ffa97ceeb49e29780f25fe6c87640 task 36f9689711254f0e9d933890a06a9f45 task f5dd3dad76924f9f8f68e0d725a770c0.
  10:47:41 service my-service registered 3 targets in target-group my-tg
  10:47:52 service my-service registered 2 targets in target-group my-tg
  10:49:05 service my-service has reached a steady state.
      NOTE: starting the tasks took 33 seconds, this is very acceptable because I set the HealthCheckGracePeriodSeconds to 30 seconds and health check interval is 30 seconds as well)
      NOTE: 3m09s between the time the load starting pounding the server and the time the first new ECS tasks are up
      NOTE: most of this time (3m09s) is due to the waiting for the alarm to go off (2m20s)!! The rest is normal: waiting for the new tasks to start. 
  

  Q1:有没有办法让警报更快地触发和/或在阈值被突破时立即触发?对我来说，这太需要 1 分 20 秒了.它真的应该在 1 分 30 秒左右(最多 1 米以检测 ALARM HIGH 状态 + 30 秒以启动任务)...

  Q1: Is there a way to make the alarm trigger faster and/or as soon as the threshold is breached? To me, this is taking 1m20s too much. It should really scale up in around 1m30s (1m max to detect the ALARM HIGH state + 30 seconds to start the task)...

  注意:我在今天打开的另一个问题中记录了我的 CloudFormation 堆栈:Cloudformation ECS Fargate 自动缩放目标跟踪:11 分钟内自定义警报:无法执行操作

  Note: I documented my CloudFormation stack in this other question I opened today: Cloudformation ECS Fargate autoscaling target tracking: 1 custom alarm in 1 minute: Failed to execute action

  推荐答案

  对此您无能为力.ALB 以 1 分钟间隔向 CloudWatch 发送指标.此外，这些指标无论如何不是实时，因此预计会出现延迟，甚至会像 AWS 支持部门解释的那样长达几分钟，并在评论中报告 此处:

  You can't do much about it. ALB sends metrics to CloudWatch in 1 minute intervals. Also these metrics are not real-time anyway, so delays are expected, even up to few minutes as explained by AWS support and reported in the comments here:

  预计会有一些指标延迟，这对于任何监控系统都是固有的 - 因为它们取决于多个变量，例如服务发布指标的延迟、传播延迟和 CloudWatch 中的摄取延迟等等.我确实理解 ALB 指标的持续3 或 4 分钟延迟会更高.

  Some delay in metrics is expected, which is inherent for any monitoring systems- as they depend on several variables such as delay with the service publishing the metric, propagation delays and ingestion delay within CloudWatch to name a few. I do understand that a consistent 3 or 4 minute delay for ALB metrics is on the higher side.

  您要么必须过度配置 ECS 以在警报触发和升级执行时承受增加的负载，要么降低阈值.

  You would either have to over-provision your ECS to sustain the increased load by the time the alarms fires and the up-scaling executes, or reduce your thresholds.

  或者，您可以创建自己的自定义指标，例如从你的应用程序.这些指标甚至可以有 1 秒的间隔.您的应用程序还可以手动"触发警报.这可以让您减少观察到的延迟.

  Alternative, you can create your own custom metrics, e.g. from your app. These metrics can be even with 1 second intervals. Your app could also "manually" trigger the alarm. This would allow you to reduce the delay you observe.

  这篇关于ECS Fargate 自动扩展更快?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！