AWS CloudWatch Alarms, Events, and EventBridge

CloudWatch alarms

CloudWatch alarms monitor a single AWS metric and trigger actions (Lambda functions, scaling actions, CloudWatch Events, and more) if it crosses a defined threshold. A CloudWatch alarm can be in one of three states:

• OK: The metric is within the defined threshold.
• ALARM: The metric is breaching the defined threshold.
• INSUFFICIENT_DATA: The metric is unavailable, or the alarm was just created, and it doesn’t have sufficient data to determine an alarm state.

When creating the alarm, we have to specify its period, evaluation period, and data points. Knowing these settings is essential for the exam.

• Period: The length of time to evaluate the metric to create a data point in the alarm. This value is specified in seconds.
• Evaluation period: The number of most recent periods that are considered when determining the alarm state.
• Data points to alarm: The number of data points in the evaluation period that have to breach the threshold to go to the ALARM state.

If a data point is unavailable in a metric for any reason, it’s ...