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AWS::EMR::Cluster CloudWatchAlarmDefinition
CloudWatchAlarmDefinition is a subproperty of the  ScalingTrigger property, which determines when to trigger an automatic scaling activity. Scaling activity begins when you satisfy the defined alarm conditions.
Syntax
To declare this entity in your AWS CloudFormation template, use the following syntax:
JSON
{ "ComparisonOperator" :String, "Dimensions" :[ MetricDimension, ... ], "EvaluationPeriods" :Integer, "MetricName" :String, "Namespace" :String, "Period" :Integer, "Statistic" :String, "Threshold" :Number, "Unit" :String}
YAML
ComparisonOperator:StringDimensions:- MetricDimensionEvaluationPeriods:IntegerMetricName:StringNamespace:StringPeriod:IntegerStatistic:StringThreshold:NumberUnit:String
Properties
- ComparisonOperator
- 
                    Determines how the metric specified by MetricNameis compared to the value specified byThreshold.Required: Yes Type: String Allowed values: GREATER_THAN_OR_EQUAL | GREATER_THAN | LESS_THAN | LESS_THAN_OR_EQUALUpdate requires: No interruption 
- Dimensions
- 
                    A CloudWatch metric dimension. Required: No Type: Array of MetricDimension Update requires: No interruption 
- EvaluationPeriods
- 
                    The number of periods, in five-minute increments, during which the alarm condition must exist before the alarm triggers automatic scaling activity. The default value is 1.Required: No Type: Integer Update requires: No interruption 
- MetricName
- 
                    The name of the CloudWatch metric that is watched to determine an alarm condition. Required: Yes Type: String Update requires: No interruption 
- Namespace
- 
                    The namespace for the CloudWatch metric. The default is AWS/ElasticMapReduce.Required: No Type: String Update requires: No interruption 
- Period
- 
                    The period, in seconds, over which the statistic is applied. CloudWatch metrics for Amazon EMR are emitted every five minutes (300 seconds), so if you specify a CloudWatch metric, specify 300.Required: Yes Type: Integer Update requires: No interruption 
- Statistic
- 
                    The statistic to apply to the metric associated with the alarm. The default is AVERAGE.Required: No Type: String Allowed values: SAMPLE_COUNT | AVERAGE | SUM | MINIMUM | MAXIMUMUpdate requires: No interruption 
- Threshold
- 
                    The value against which the specified statistic is compared. Required: Yes Type: Number Update requires: No interruption 
- Unit
- 
                    The unit of measure associated with the CloudWatch metric being watched. The value specified for Unitmust correspond to the units specified in the CloudWatch metric.Required: No Type: String Allowed values: NONE | SECONDS | MICRO_SECONDS | MILLI_SECONDS | BYTES | KILO_BYTES | MEGA_BYTES | GIGA_BYTES | TERA_BYTES | BITS | KILO_BITS | MEGA_BITS | GIGA_BITS | TERA_BITS | PERCENT | COUNT | BYTES_PER_SECOND | KILO_BYTES_PER_SECOND | MEGA_BYTES_PER_SECOND | GIGA_BYTES_PER_SECOND | TERA_BYTES_PER_SECOND | BITS_PER_SECOND | KILO_BITS_PER_SECOND | MEGA_BITS_PER_SECOND | GIGA_BITS_PER_SECOND | TERA_BITS_PER_SECOND | COUNT_PER_SECONDUpdate requires: No interruption