AWS::CloudWatch::Alarm Dimension

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Dimension is an embedded property of the AWS::CloudWatch::Alarm type. Dimensions are name/value pairs that can be associated with a CloudWatch metric. You can specify a maximum of 30 dimensions for a given metric.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{
  "Name" : String,
  "Value" : String
}

YAML

  Name: String
  Value: String

Properties

Name

The name of the dimension, from 1–255 characters in length. This dimension name must have been included when the metric was published.

Required: Yes

Type: String

Minimum: 1

Maximum: 255

Update requires: No interruption

Value

The value for the dimension, from 1–255 characters in length.

Required: Yes

Type: String

Minimum: 1

Maximum: 1024

Update requires: No interruption

Examples

Two alarms with dimension values supplied by the Ref function

The Ref and GetAtt intrinsic functions are often used to supply values for CloudWatch metric dimensions. Here is an example using the Ref function.

JSON

{
    "CPUAlarmHigh": {
        "Type": "AWS::CloudWatch::Alarm",
        "Properties": {
            "AlarmDescription": "Scale-up if CPU is greater than 90% for 10 minutes",
            "MetricName": "CPUUtilization",
            "Namespace": "AWS/EC2",
            "Statistic": "Average",
            "Period": "300",
            "EvaluationPeriods": "2",
            "Threshold": "90",
            "AlarmActions": [
                {
                    "Ref": "WebServerScaleUpPolicy"
                }
            ],
            "Dimensions": [
                {
                    "Name": "AutoScalingGroupName",
                    "Value": {
                        "Ref": "WebServerGroup"
                    }
                }
            ],
            "ComparisonOperator": "GreaterThanThreshold"
        }
    },
    "CPUAlarmLow": {
        "Type": "AWS::CloudWatch::Alarm",
        "Properties": {
            "AlarmDescription": "Scale-down if CPU is less than 70% for 10 minutes",
            "MetricName": "CPUUtilization",
            "Namespace": "AWS/EC2",
            "Statistic": "Average",
            "Period": "300",
            "EvaluationPeriods": "2",
            "Threshold": "70",
            "AlarmActions": [
                {
                    "Ref": "WebServerScaleDownPolicy"
                }
            ],
            "Dimensions": [
                {
                    "Name": "AutoScalingGroupName",
                    "Value": {
                        "Ref": "WebServerGroup"
                    }
                }
            ],
            "ComparisonOperator": "LessThanThreshold"
        }
    }
}

YAML

CPUAlarmHigh:
  Type: 'AWS::CloudWatch::Alarm'
  Properties:
    AlarmDescription: Scale-up if CPU is greater than 90% for 10 minutes
    MetricName: CPUUtilization
    Namespace: AWS/EC2
    Statistic: Average
    Period: '300'
    EvaluationPeriods: '2'
    Threshold: '90'
    AlarmActions:
      - !Ref WebServerScaleUpPolicy
    Dimensions:
      - Name: AutoScalingGroupName
        Value: !Ref WebServerGroup
    ComparisonOperator: GreaterThanThreshold
CPUAlarmLow:
  Type: 'AWS::CloudWatch::Alarm'
  Properties:
    AlarmDescription: Scale-down if CPU is less than 70% for 10 minutes
    MetricName: CPUUtilization
    Namespace: AWS/EC2
    Statistic: Average
    Period: '300'
    EvaluationPeriods: '2'
    Threshold: '70'
    AlarmActions:
      - !Ref WebServerScaleDownPolicy
    Dimensions:
      - Name: AutoScalingGroupName
        Value: !Ref WebServerGroup
    ComparisonOperator: LessThanThreshold