Amazon CloudWatch
API Reference (API Version 2010-08-01)
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PutMetricAlarm

Creates or updates an alarm and associates it with the specified metric, metric math expression, or anomaly detection model.

Alarms based on anomaly detection models cannot have Auto Scaling actions.

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.

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

If you are an IAM user, you must have Amazon EC2 permissions for some alarm operations:

  • iam:CreateServiceLinkedRole for all alarms with EC2 actions

  • ec2:DescribeInstanceStatus and ec2:DescribeInstances for all alarms on EC2 instance status metrics

  • ec2:StopInstances for alarms with stop actions

  • ec2:TerminateInstances for alarms with terminate actions

  • No specific permissions are needed for alarms with recover actions

If you have read/write permissions for Amazon CloudWatch but not for Amazon EC2, you can still create an alarm, but the stop or terminate actions are not performed. However, if you are later granted the required permissions, the alarm actions that you created earlier are performed.

If you are using an IAM role (for example, an EC2 instance profile), you cannot stop or terminate the instance using alarm actions. However, you can still see the alarm state and perform any other actions such as Amazon SNS notifications or Auto Scaling policies.

If you are using temporary security credentials granted using AWS STS, you cannot stop or terminate an EC2 instance using alarm actions.

The first time you create an alarm in the AWS Management Console, the CLI, or by using the PutMetricAlarm API, CloudWatch creates the necessary service-linked role for you. The service-linked role is called AWSServiceRoleForCloudWatchEvents. For more information, see AWS service-linked role.

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. 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:automate:region:ec2:stop | arn:aws:automate:region:ec2:terminate | arn:aws:automate:region:ec2:recover | arn:aws:automate:region:ec2:reboot | arn:aws:sns:region:account-id:sns-topic-name | arn:aws:autoscaling:region:account-id:scalingPolicy:policy-idautoScalingGroupName/group-friendly-name:policyName/policy-friendly-name

Valid Values (for use with IAM roles): arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Stop/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Terminate/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Reboot/1.0

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 alarm.

Type: String

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

Required: No

AlarmName

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

Type: String

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

Required: Yes

ComparisonOperator

The arithmetic operation to use when comparing the specified statistic and threshold. The specified statistic value is used as the first operand.

The values LessThanLowerOrGreaterThanUpperThreshold, LessThanLowerThreshold, and GreaterThanUpperThreshold are used only for alarms based on anomaly detection models.

Type: String

Valid Values: GreaterThanOrEqualToThreshold | GreaterThanThreshold | LessThanThreshold | LessThanOrEqualToThreshold | LessThanLowerOrGreaterThanUpperThreshold | LessThanLowerThreshold | GreaterThanUpperThreshold

Required: Yes

DatapointsToAlarm

The number of datapoints that must be breaching to trigger the alarm. This is used only if you are setting an "M out of N" alarm. In that case, this value is the M. For more information, see Evaluating an Alarm in the Amazon CloudWatch User Guide.

Type: Integer

Valid Range: Minimum value of 1.

Required: No

Dimensions.member.N

The dimensions for the metric specified in MetricName.

Type: Array of Dimension objects

Array Members: Maximum number of 10 items.

Required: No

EvaluateLowSampleCountPercentile

Used only for alarms based on percentiles. If you specify ignore, the alarm state does not change during periods with too few data points to be statistically significant. If you specify evaluate or omit this parameter, the alarm is always evaluated and possibly changes state no matter how many data points are available. For more information, see Percentile-Based CloudWatch Alarms and Low Data Samples.

Valid Values: evaluate | ignore

Type: String

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

Required: No

EvaluationPeriods

The number of periods over which data is compared to the specified threshold. If you are setting an alarm that requires that a number of consecutive data points be breaching to trigger the alarm, this value specifies that number. If you are setting an "M out of N" alarm, this value is the N.

An alarm's total current evaluation period can be no longer than one day, so this number multiplied by Period cannot be more than 86,400 seconds.

Type: Integer

Valid Range: Minimum value of 1.

Required: Yes

ExtendedStatistic

The percentile statistic for the metric specified in MetricName. Specify a value between p0.0 and p100. When you call PutMetricAlarm and specify a MetricName, you must specify either Statistic or ExtendedStatistic, but not both.

Type: String

Pattern: p(\d{1,2}(\.\d{0,2})?|100)

Required: No

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:automate:region:ec2:stop | arn:aws:automate:region:ec2:terminate | arn:aws:automate:region:ec2:recover | arn:aws:automate:region:ec2:reboot | arn:aws:sns:region:account-id:sns-topic-name | arn:aws:autoscaling:region:account-id:scalingPolicy:policy-idautoScalingGroupName/group-friendly-name:policyName/policy-friendly-name

Valid Values (for use with IAM roles): >arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Stop/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Terminate/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Reboot/1.0

Type: Array of strings

Array Members: Maximum number of 5 items.

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

Required: No

MetricName

The name for the metric associated with the alarm. For each PutMetricAlarm operation, you must specify either MetricName or a Metrics array.

If you are creating an alarm based on a math expression, you cannot specify this parameter, or any of the Dimensions, Period, Namespace, Statistic, or ExtendedStatistic parameters. Instead, you specify all this information in the Metrics array.

Type: String

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

Required: No

Metrics.member.N

An array of MetricDataQuery structures that enable you to create an alarm based on the result of a metric math expression. For each PutMetricAlarm operation, you must specify either MetricName or a Metrics array.

Each item in the Metrics array either retrieves a metric or performs a math expression.

One item in the Metrics array is the expression that the alarm watches. You designate this expression by setting ReturnValue to true for this object in the array. For more information, see MetricDataQuery.

If you use the Metrics parameter, you cannot include the MetricName, Dimensions, Period, Namespace, Statistic, or ExtendedStatistic parameters of PutMetricAlarm in the same operation. Instead, you retrieve the metrics you are using in your math expression as part of the Metrics array.

Type: Array of MetricDataQuery objects

Required: No

Namespace

The namespace for the metric associated specified in MetricName.

Type: String

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

Pattern: [^:].*

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:automate:region:ec2:stop | arn:aws:automate:region:ec2:terminate | arn:aws:automate:region:ec2:recover | arn:aws:automate:region:ec2:reboot | arn:aws:sns:region:account-id:sns-topic-name | arn:aws:autoscaling:region:account-id:scalingPolicy:policy-idautoScalingGroupName/group-friendly-name:policyName/policy-friendly-name

Valid Values (for use with IAM roles): arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Stop/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Terminate/1.0 | arn:aws:swf:region:account-id:action/actions/AWS_EC2.InstanceId.Reboot/1.0

Type: Array of strings

Array Members: Maximum number of 5 items.

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

Required: No

Period

The length, in seconds, used each time the metric specified in MetricName is evaluated. Valid values are 10, 30, and any multiple of 60.

Period is required for alarms based on static thresholds. If you are creating an alarm based on a metric math expression, you specify the period for each metric within the objects in the Metrics array.

Be sure to specify 10 or 30 only for metrics that are stored by a PutMetricData call with a StorageResolution of 1. If you specify a period of 10 or 30 for a metric that does not have sub-minute resolution, the alarm still attempts to gather data at the period rate that you specify. In this case, it does not receive data for the attempts that do not correspond to a one-minute data resolution, and the alarm may often lapse into INSUFFICENT_DATA status. Specifying 10 or 30 also sets this alarm as a high-resolution alarm, which has a higher charge than other alarms. For more information about pricing, see Amazon CloudWatch Pricing.

An alarm's total current evaluation period can be no longer than one day, so Period multiplied by EvaluationPeriods cannot be more than 86,400 seconds.

Type: Integer

Valid Range: Minimum value of 1.

Required: No

Statistic

The statistic for the metric specified in MetricName, other than percentile. For percentile statistics, use ExtendedStatistic. When you call PutMetricAlarm and specify a MetricName, you must specify either Statistic or ExtendedStatistic, but not both.

Type: String

Valid Values: SampleCount | Average | Sum | Minimum | Maximum

Required: No

Tags.member.N

A list of key-value pairs to associate with the 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

Threshold

The value against which the specified statistic is compared.

This parameter is required for alarms based on static thresholds, but should not be used for alarms based on anomaly detection models.

Type: Double

Required: No

ThresholdMetricId

If this is an alarm based on an anomaly detection model, make this value match the ID of the ANOMALY_DETECTION_BAND function.

For an example of how to use this parameter, see the Anomaly Detection Model Alarm example on this page.

If your alarm uses this parameter, it cannot have Auto Scaling actions.

Type: String

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

Required: No

TreatMissingData

Sets how this alarm is to handle missing data points. If TreatMissingData is omitted, the default behavior of missing is used. For more information, see Configuring How CloudWatch Alarms Treats Missing Data.

Valid Values: breaching | notBreaching | ignore | missing

Type: String

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

Required: No

Unit

The unit of measure for the statistic. For example, the units for the Amazon EC2 NetworkIn metric are Bytes because NetworkIn tracks the number of bytes that an instance receives on all network interfaces. You can also specify a unit when you create a custom metric. Units help provide conceptual meaning to your data. Metric data points that specify a unit of measure, such as Percent, are aggregated separately.

If you don't specify Unit, CloudWatch retrieves all unit types that have been published for the metric and attempts to evaluate the alarm. Usually metrics are published with only one unit, so the alarm will work as intended.

However, if the metric is published with multiple types of units and you don't specify a unit, the alarm's behavior is not defined and will behave un-predictably.

We recommend omitting Unit so that you don't inadvertently specify an incorrect unit that is not published for this metric. Doing so causes the alarm to be stuck in the INSUFFICIENT DATA state.

Type: String

Valid Values: Seconds | Microseconds | Milliseconds | Bytes | Kilobytes | Megabytes | Gigabytes | Terabytes | Bits | Kilobits | Megabits | Gigabits | Terabits | Percent | Count | Bytes/Second | Kilobytes/Second | Megabytes/Second | Gigabytes/Second | Terabytes/Second | Bits/Second | Kilobits/Second | Megabits/Second | Gigabits/Second | Terabits/Second | Count/Second | None

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

Examples

Static Threshold Alarm

The following example creates an alarm that notifies an SNS group when the CPUUtilization of a certain instance goes over 40% for three out of four periods.

Sample Request

{ "Namespace": "AWS/EC2", "MetricName": "CPUUtilization", "Dimensions": [ { "Name": "InstanceId", "Value": "i-1234567890abcdef0" } ], "AlarmActions": [ "arn:aws:sns:us-west-1:123456789012:my_sns_topic" ], "ComparisonOperator": "GreaterThanThreshold", "DatapointsToAlarm": 3, "EvaluationPeriods": 4, "Period": 60, "Statistic": "Average", "Threshold": 40, "AlarmDescription": "CPU Utilization of i-1234567890abcdef0 with 40% as threshold", "AlarmName": "Instance i-1234567890abcdef0 CPU Utilization" }

Metric Math Function Alarm

The following example retrieves three metrics that each track a different type of connection error to a custom service. These error counts are first summed in one expression, then divided by total connection attempts in another expression. The alarm goes to the ALARM state if the error rate is over 3% for two consecutive periods, and notifies two different SNS groups.

Sample Request

{ "AlarmActions": [ "arn:aws:sns:us-west-1:123456789012:my_sns_topic", "arn:aws:sns:us-west-1:123456789012:my_other_sns_topic" ], "ComparisonOperator": "GreaterThanThreshold", "EvaluationPeriods": 3, "Threshold": 40, "AlarmDescription": "MyService Aggregate Connection Error Rate (Alarm at 3%)", "AlarmName": "MyService Connection Error Rate", "Metrics": [ { "MetricStat": { "Metric": { "MetricName": "ConnectionsFailed", "Namespace": "MyService" }, "Period": 60, "Stat": "Sum" }, "Id": "m1", "ReturnData": "False" }, { "MetricStat": { "Metric": { "MetricName": "ConnectionsDropped", "Namespace": "MyService" }, "Period": 60, "Stat": "Sum" }, "Id": "m2", "ReturnData": "False" }, { "MetricStat": { "Metric": { "MetricName": "RequestsThrottled", "Namespace": "MyService" }, "Period": 60, "Stat": "Sum" }, "Id": "m3", "ReturnData": "False" }, { "MetricStat": { "Metric": { "MetricName": "ConnectionAttempts", "Namespace": "MyService" }, "Period": 60, "Stat": "Sum" }, "Id": "m4", "ReturnData": "False" }, { "Id": "error_total", "Expression": "m1+m2+m3", "ReturnData": "False" }, { "Id": "error_rate", "Expression": "(error_total/m4)*100", "ReturnData": "True", "Label": "Total Connection Error Rate" } ] }

Anomaly Detection Model Alarm

The following example sets an alarm on an anomaly detection model. The Id of m1 is assigned to the CPUUtilization metric of an instance. t1 is the anomaly detection model function for that metric, and uses 3 standard deviations to set the width of the band. The setting of ThresholdMetricId is t1 and the ComparisonOperator is LessThanLowerOrGreaterThanUpperThreshold, specifying that the alarm goes to alarm state when the metric value is outside the anomaly model band in either direction for two consecutive evaluation periods.

Sample Request

{ "AlarmActions": [ "arn:aws:sns:us-west-1:123456789012:my_sns_topic", "arn:aws:sns:us-west-1:123456789012:my_other_sns_topic" ], "AlarmName": "MyAlarmName", "AlarmDescription": "This alarm uses an anomaly detection model", "Metrics": [ { "Id": "m1", "ReturnData": true, "MetricStat": { "Metric": { "MetricName": "CPUUtilization", "Namespace": "AWS/EC2", "Dimensions": [ { "Name": "instanceId", "Value": "i-1234567890abcdef0" } ] }, "Statistic": "Average", "Period": 60 } }, { "Id": "t1", "Expression": "ANOMALY_DETECTION_BAND(m1, 3)" } ], "EvaluationPeriods": 2, "ThresholdMetricId": "t1", "ComparisonOperator": "LessThanLowerOrGreaterThanUpperThreshold" }

See Also

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