PutCompositeAlarm - Amazon CloudWatch

PutCompositeAlarm

Creates or updates a composite alarm. When you create a composite alarm, you specify a rule expression for the alarm that takes into account the alarm states of other alarms that you have created. The composite alarm goes into ALARM state only if all conditions of the rule are met.

The alarms specified in a composite alarm's rule expression can include metric alarms and other composite alarms.

Using composite alarms can reduce alarm noise. You can create multiple metric alarms, and also create a composite alarm and set up alerts only for the composite alarm. For example, you could create a composite alarm that goes into ALARM state only when more than one of the underlying metric alarms are in ALARM state.

Currently, the only alarm actions that can be taken by composite alarms are notifying SNS topics.

Note

It is possible to create a loop or cycle of composite alarms, where composite alarm A depends on composite alarm B, and composite alarm B also depends on composite alarm A. In this scenario, you can't delete any composite alarm that is part of the cycle because there is always still a composite alarm that depends on that alarm that you want to delete.

To get out of such a situation, you must break the cycle by changing the rule of one of the composite alarms in the cycle to remove a dependency that creates the cycle. The simplest change to make to break a cycle is to change the AlarmRule of one of the alarms to False.

Additionally, the evaluation of composite alarms stops if CloudWatch detects a cycle in the evaluation path.

When this operation creates an alarm, the alarm state is immediately set to INSUFFICIENT_DATA. The alarm is then evaluated and its state is set appropriately. Any actions associated with the new state are then executed. For a composite alarm, this initial time after creation is the only time that the alarm can be in INSUFFICIENT_DATA state.

When you update an existing alarm, its state is left unchanged, but the update completely overwrites the previous configuration of the alarm.

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

ActionsEnabled

Indicates whether actions should be executed during any changes to the alarm state of the composite alarm. The default is TRUE.

Type: Boolean

Required: No

AlarmActions.member.N

The actions to execute when this alarm transitions to the ALARM state from any other state. Each action is specified as an Amazon Resource Name (ARN).

Valid Values: arn:aws:sns:region:account-id:sns-topic-name

Type: Array of strings

Array Members: Maximum number of 5 items.

Length Constraints: Minimum length of 1. Maximum length of 1024.

Required: No

AlarmDescription

The description for the composite alarm.

Type: String

Length Constraints: Minimum length of 0. Maximum length of 1024.

Required: No

AlarmName

The name for the composite alarm. This name must be unique within your AWS account.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 255.

Required: Yes

AlarmRule

An expression that specifies which other alarms are to be evaluated to determine this composite alarm's state. For each alarm that you reference, you designate a function that specifies whether that alarm needs to be in ALARM state, OK state, or INSUFFICIENT_DATA state. You can use operators (AND, OR and NOT) to combine multiple functions in a single expression. You can use parenthesis to logically group the functions in your expression.

You can use either alarm names or ARNs to reference the other alarms that are to be evaluated.

Functions can include the following:

  • ALARM("alarm-name or alarm-ARN") is TRUE if the named alarm is in ALARM state.

  • OK("alarm-name or alarm-ARN") is TRUE if the named alarm is in OK state.

  • INSUFFICIENT_DATA("alarm-name or alarm-ARN") is TRUE if the named alarm is in INSUFFICIENT_DATA state.

  • TRUE always evaluates to TRUE.

  • FALSE always evaluates to FALSE.

TRUE and FALSE are useful for testing a complex AlarmRule structure, and for testing your alarm actions.

Alarm names specified in AlarmRule can be surrounded with double-quotes ("), but do not have to be.

The following are some examples of AlarmRule:

  • ALARM(CPUUtilizationTooHigh) AND ALARM(DiskReadOpsTooHigh) specifies that the composite alarm goes into ALARM state only if both CPUUtilizationTooHigh and DiskReadOpsTooHigh alarms are in ALARM state.

  • ALARM(CPUUtilizationTooHigh) AND NOT ALARM(DeploymentInProgress) specifies that the alarm goes to ALARM state if CPUUtilizationTooHigh is in ALARM state and DeploymentInProgress is not in ALARM state. This example reduces alarm noise during a known deployment window.

  • (ALARM(CPUUtilizationTooHigh) OR ALARM(DiskReadOpsTooHigh)) AND OK(NetworkOutTooHigh) goes into ALARM state if CPUUtilizationTooHigh OR DiskReadOpsTooHigh is in ALARM state, and if NetworkOutTooHigh is in OK state. This provides another example of using a composite alarm to prevent noise. This rule ensures that you are not notified with an alarm action on high CPU or disk usage if a known network problem is also occurring.

The AlarmRule can specify as many as 100 "children" alarms. The AlarmRule expression can have as many as 500 elements. Elements are child alarms, TRUE or FALSE statements, and parentheses.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 10240.

Required: Yes

InsufficientDataActions.member.N

The actions to execute when this alarm transitions to the INSUFFICIENT_DATA state from any other state. Each action is specified as an Amazon Resource Name (ARN).

Valid Values: arn:aws:sns:region:account-id:sns-topic-name

Type: Array of strings

Array Members: Maximum number of 5 items.

Length Constraints: Minimum length of 1. Maximum length of 1024.

Required: No

OKActions.member.N

The actions to execute when this alarm transitions to an OK state from any other state. Each action is specified as an Amazon Resource Name (ARN).

Valid Values: arn:aws:sns:region:account-id:sns-topic-name

Type: Array of strings

Array Members: Maximum number of 5 items.

Length Constraints: Minimum length of 1. Maximum length of 1024.

Required: No

Tags.member.N

A list of key-value pairs to associate with the composite alarm. You can associate as many as 50 tags with an alarm.

Tags can help you organize and categorize your resources. You can also use them to scope user permissions, by granting a user permission to access or change only resources with certain tag values.

Type: Array of Tag objects

Required: No

Errors

For information about the errors that are common to all actions, see Common Errors.

LimitExceeded

The quota for alarms for this customer has already been reached.

HTTP Status Code: 400

Example

Composite alarm example

The following example creates an alarm that notifies an SNS group when either of two specified metric alarms exceeds its threshold.

Sample Request

{ "AlarmDescription": "The host is experiencing problems", "AlarmRule": "ALARM(CPUUtilizationTooHigh) OR ALARM(DiskReadOpsTooHigh)", "AlarmName": "overall-health-alarm", "AlarmActions": [ "arn:aws:sns:us-west-1:123456789012:my_sns_topic" ] }

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: