Create a composite alarm

To create a composite alarm

1. Open the CloudWatch console at https://console.amazonaws.cn/cloudwatch/.

2. In the navigation pane, choose Alarms, and then choose All alarms.

3. From the list of alarms, select the check box next to each of the existing alarms that you want to reference in your rule expression, and then choose Create composite alarm.

4. Under Specify composite alarm conditions, specify the rule expression for your new composite alarm.

   Note

   Automatically, the alarms that you selected from the list of alarms are listed in the Conditions box. By default, the ALARM function has been designated to each of your alarms, and each of your alarms is joined by the logical operator OR.

   You can use the following substeps to modify your rule expression:

   1. You can change the required state for each of your alarms from ALARM to OK or INSUFFICENT_DATA.

   2. You can change the logical operator in your rule expression from OR to AND or NOT, and you can add parentheses to group your functions.

   3. You can include other alarms in your rule expression or delete alarms from your rule expression.

   Example: Rule expression with conditions

   (ALARM("CPUUtilizationTooHigh") OR 
   ALARM("DiskReadOpsTooHigh")) AND 
   OK("NetworkOutTooHigh")

   In the example rule expression where the composite alarm goes into ALARM when ALARM ("CPUUtilizationTooHigh" or ALARM("DiskReadOpsTooHigh") is in ALARM at the same time as OK("NetworkOutTooHigh") is in OK.

5. When finished, choose Next.

6. Under Configure actions, you can choose from the following:

   For Notification

   • Select an exisiting SNS topic, Create a new SNS topic, or Use a topic ARN to define the SNS topic that will receive the notification.

   • Add notification, so your alarm can send multiple notifications for the same alarm state or different alarm states.

   • Remove to stop your alarm from sending notifications or taking actions.

   (Optional) To have the alarm invoke a Lambda function when it changes state, choose Add Lambda action. Then specify the function name or ARN, and optionally choose a specific version of the function.

   For Systems Manager action

   • Add Systems Manager action, so your alarm can perform an SSM action when it goes into ALARM.

   To learn more about Systems Manager actions, see Configuring CloudWatch to create OpsItems from alarms in the Amazon Systems Manager User Guide and Incident creation in the Incident Manager User Guide. To create an alarm that performs an SSM Incident Manager action, you must have the correct permissions. For more information, see Identity-based policy examples for Amazon Systems Manager Incident Manager in the Incident Manager User Guide.

7. When finished, choose Next.

8. Under Add name and description, enter an alarm name and optional description for your new composite alarm. The name must contain only UTF-8 characters, and can't contain ASCII control characters. The description can include markdown formatting, which is displayed only in the alarm Details tab in the CloudWatch console. The markdown can be useful to add links to runbooks or other internal resources.

9. When finished, choose Next.

10. Under Preview and create, confirm your information, and then choose Create composite alarm.

    Note

    You can create a cycle of composite alarms, where one composite alarm and another composite alarm depend on each other. If you find yourself in this scenario, your composite alarms stop being evaluated, and you can't delete your composite alarms because they're dependent on each other. The easiest way to break the cycle of dependecy between your composite alarms is to change the function AlarmRule in one of your composite alarms to False.