Acting on alarm changes - Amazon CloudWatch
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Acting on alarm changes

CloudWatch can notify users on two types of alarm changes: when an alarm changes state, and when the configuration of an alarm gets updated.

When an alarm evaluates, it might change from one state to another, such as ALARM or OK. For Metrics Insights alarms that monitor multiple time series, each time series (contributor) can only be in ALARM or OK state, never in INSUFFICIENT_DATA state. This is because a time series only exists when data is present.

Additionally, CloudWatch sends events to Amazon EventBridge whenever alarms change state, and when alarms are created, deleted, or updated. You can write EventBridge rules to take actions or be notified when EventBridge receives these events.

For more information about alarm actions, see Alarm actions.

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