Monitoring
You can monitor Amazon DocumentDB using several methods. You can monitor the health and status of your Amazon DocumentDB cluster and your Amazon DocumentDB instances using the AWS Management Console or the AWS CLI. Amazon DocumentDB integrates with Amazon CloudWatch and you can monitor performance metrics like CPU utilization, memory, IOPS, and network throughput using Amazon CloudWatch.

Amazon DocumentDB CloudWatch metrics
Amazon DocumentDB tracks the events related to your cluster. You can view the history of the events
including details on snapshot creation, failover, instance reboots, and any modifications to
your cluster. You can use the AWS Management Console or the AWS CLI (describe-events
command) to view these
event details.
Using Event Subscriptions, you can also sign up to receive notifications for management
events that occur on your Amazon DocumentDB clusters, instances, cluster snapshots, and parameter groups.
Whenever events occur, Amazon DocumentDB uses Amazon Simple Notification Service