How to install the custom CloudWatch script and log the disk utilization metric to Cloudwatch

How to install the custom CloudWatch script and log the disk utilization metric to Cloudwatch

By default, CloudWatch does not log disk space utilization metric. However, there is a custom CloudWatch script that can be used to push the disk space utilization metric to CloudWatch which can then be used to create an SNS notification which would send you an alarm.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/mon-scripts.html.

You can setup a threshold on the disk space utilization metric (in this case, you ca set the threshold to >=88% so that it can notify you before the disk becomes full) in Cloudwatch alarms which can trigger a notification to an SNS topic that you specify.