Lightsail system disk alarm

Question

I need to receive an email when my the system disk on my Lightsail instance is 90% full. Could someone please advise how I might set an alarm to achieve this? When I login to my Lightsail instance, under the Metrics tab, I only seem to be able to set alarms for "CPU utilization" and "CPU burst capacity (percentage)".

Answer

Hello.

As you may know, Lightsail metrics do not include disk usage.  
https://lightsail.aws.amazon.com/ls/docs/en_us/articles/amazon-lightsail-resource-health-metrics

Therefore, as introduced in the document below, you need to install CloudWatch Agent and output disk usage to CloudWatch before creating an alarm.  
Also, unlike EC2, Lightsail cannot set IAM roles, so you need to create and set access keys from IAM users.  
https://aws.amazon.com/jp/blogs/compute/monitoring-memory-usage-lightsail-instance/
https://repost.aws/knowledge-center/lightsail-monitor-with-cloudwatch

Lightsail system disk alarm

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