Creating ALB and ASGs LAB - AWS CSA 2018 Course

Hi, 
Anyone else have isues with their auto scaling group instances automatically terminate and / or spin up new instances on their own?  I was following this lab, and was on the last video where I terminated an instance so that auto scaling would spin up a new instance.  A new instance did get spun up, however about 5 minutes later, one of my running instances terminated without me doing anything, which resulted in another instance to be created.  I re-did the lab, and this time, instead of an instance being terminatd, another instance was created without me doing anything.  My alarm was for the CPU utilization to be above 80 and below 50% to either spin up or spin down, but i doubt these thresholds were broken when I noticed this weird behavior.  Let me know if anyone else has experienced this, thanks!
  • post-author-pic
    Craig A
    11-29-2018

    Hello John. The most likely cause for the instance terminating was a failed Health Check. It may have been an intermittent network issue which casued the Health Check to fail. This is a nice little article on how you can further investigate what happened:

    https://aws.amazon.com/premiumsupport/knowledge-center/auto-scaling-instance-how-terminated/


    And it is something I will strongly consider adding to the Learning Activity.


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