# ScalingTrigger
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The conditions that trigger an automatic scaling activity.

## Contents
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 ** CloudWatchAlarmDefinition **   <a name="EMR-Type-ScalingTrigger-CloudWatchAlarmDefinition"></a>
The definition of a CloudWatch metric alarm. When the defined alarm conditions are met along with other trigger parameters, scaling activity begins.  
Type: [CloudWatchAlarmDefinition](API_CloudWatchAlarmDefinition.md) object  
Required: Yes

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/elasticmapreduce-2009-03-31/ScalingTrigger) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/elasticmapreduce-2009-03-31/ScalingTrigger) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/elasticmapreduce-2009-03-31/ScalingTrigger)