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CloudWatch Alarms

  • Alarms are used to trigger notifications for any metric
  • Various options (sampling, %, max, min, etc...)
  • Alarm states:
    • OK
    • INSUFFICIENT_DATA
    • ALARM
  • Period:
    • Length of time in seconds to evaluate the metric
    • High resolution custom metrics: 10 sec, 30 sec or multiples of 60 sec

Alarm Targets

  • Stop, Terminate, Reboot or Recover an EC2 instance (EC2)
  • Trigger Auto Scaling Action (EC2 AutoScaling)
  • Send notification to SNS (from which you can do pretty much anything)

Instance Recovery

  • Status Check:
    • Instance status = check the EC2 VM
    • System status = check the underlying hardware
  • Recovery: Same private, public, elastic IP, metadata, placement group

Good to Know

  • Alarms can be created based on CloudWatch Logs Metrics Filters

  • To test alarms and notifications, set the alarm state to Alarm using CLI
$ aws cloudwatch set-alarm-state --alarm-name "myalarm" --state-value ALARM --state-reason "testing purposes"