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Amazon DynamoDB
Developer Guide (API Version 2012-08-10)

Application Programming With DynamoDB Auto Scaling

In addition to using the AWS Management Console and AWS CLI, you can write applications that interact with DynamoDB auto scaling. This section contains two Java programs that you can use to test this functionality:

  • EnableDynamoDBAutoscaling.java

  • DisableDynamoDBAutoscaling.java

Enabling Application Auto Scaling for a Table

The following program shows an example of setting up an auto scaling policy for a DynamoDB table (TestTable). It proceeds as follows:

  • The program registers write capacity units as a scalable target for TestTable. The range for this metric is between 5 and 10 write capacity units.

  • After the scalable target is created, the program builds a target tracking configuration. The policy seeks to maintain a 50 percent target ratio between consumed write capacity and provisioned write capacity.

  • The program then creates the scaling policy, based on the target tracking configuration.

The program requires that you supply an ARN for a valid Application Auto Scaling service role. (For example: "arn:aws:iam::122517410325:role/MyIAMAutoscalingServiceRole.) In the following program, replace SERVICE_ROLE_ARN_GOES_HERE with the actual ARN. For more information, see Step 1: Create a Service Role for Application Auto Scaling.

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package com.amazonaws.codesamples.autoscaling; import com.amazonaws.services.applicationautoscaling.AWSApplicationAutoScalingClient; import com.amazonaws.services.applicationautoscaling.model.DescribeScalableTargetsRequest; import com.amazonaws.services.applicationautoscaling.model.DescribeScalableTargetsResult; import com.amazonaws.services.applicationautoscaling.model.DescribeScalingPoliciesRequest; import com.amazonaws.services.applicationautoscaling.model.DescribeScalingPoliciesResult; import com.amazonaws.services.applicationautoscaling.model.MetricType; import com.amazonaws.services.applicationautoscaling.model.PolicyType; import com.amazonaws.services.applicationautoscaling.model.PredefinedMetricSpecification; import com.amazonaws.services.applicationautoscaling.model.PutScalingPolicyRequest; import com.amazonaws.services.applicationautoscaling.model.RegisterScalableTargetRequest; import com.amazonaws.services.applicationautoscaling.model.ScalableDimension; import com.amazonaws.services.applicationautoscaling.model.ServiceNamespace; import com.amazonaws.services.applicationautoscaling.model.TargetTrackingScalingPolicyConfiguration; public class EnableDynamoDBAutoscaling { static AWSApplicationAutoScalingClient aaClient = new AWSApplicationAutoScalingClient(); public static void main(String args[]) { ServiceNamespace ns = ServiceNamespace.Dynamodb; ScalableDimension tableWCUs = ScalableDimension.DynamodbTableWriteCapacityUnits; String resourceID = "table/TestTable"; // Define the scalable target RegisterScalableTargetRequest rstRequest = new RegisterScalableTargetRequest() .withServiceNamespace(ns) .withResourceId(resourceID) .withScalableDimension(tableWCUs) .withMinCapacity(5) .withMaxCapacity(10) .withRoleARN("SERVICE_ROLE_ARN_GOES_HERE"); try { aaClient.registerScalableTarget(rstRequest); } catch (Exception e) { System.err.println("Unable to register scalable target: "); System.err.println(e.getMessage()); } // Verify that the target was created DescribeScalableTargetsRequest dscRequest = new DescribeScalableTargetsRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceIds(resourceID); try { DescribeScalableTargetsResult dsaResult = aaClient.describeScalableTargets(dscRequest); System.out.println("DescribeScalableTargets result: "); System.out.println(dsaResult); System.out.println(); } catch (Exception e) { System.err.println("Unable to describe scalable target: "); System.err.println(e.getMessage()); } System.out.println(); // Configure a scaling policy TargetTrackingScalingPolicyConfiguration targetTrackingScalingPolicyConfiguration = new TargetTrackingScalingPolicyConfiguration() .withPredefinedMetricSpecification( new PredefinedMetricSpecification() .withPredefinedMetricType(MetricType. DynamoDBWriteCapacityUtilization)) .withTargetValue(50.0) .withScaleInCooldown(60) .withScaleOutCooldown(60); // Create the scaling policy, based on your configuration PutScalingPolicyRequest pspRequest = new PutScalingPolicyRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceId(resourceID) .withPolicyName("MyScalingPolicy") .withPolicyType(PolicyType.TargetTrackingScaling) .withTargetTrackingScalingPolicyConfiguration(targetTrackingScalingPolicyConfiguration); try { aaClient.putScalingPolicy(pspRequest); } catch (Exception e) { System.err.println("Unable to put scaling policy: "); System.err.println(e.getMessage()); } // Verify that the scaling policy was created DescribeScalingPoliciesRequest dspRequest = new DescribeScalingPoliciesRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceId(resourceID); try { DescribeScalingPoliciesResult dspResult = aaClient.describeScalingPolicies(dspRequest); System.out.println("DescribeScalingPolicies result: "); System.out.println(dspResult); } catch (Exception e) { e.printStackTrace(); System.err.println("Unable to describe scaling policy: "); System.err.println(e.getMessage()); } } }

Disabling Application Auto Scaling for a Table

The following program reverses the previous process. It removes the auto scaling policy, and then deregisters the scalable target.

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package com.amazonaws.codesamples.autoscaling; import com.amazonaws.services.applicationautoscaling.AWSApplicationAutoScalingClient; import com.amazonaws.services.applicationautoscaling.model.DeleteScalingPolicyRequest; import com.amazonaws.services.applicationautoscaling.model.DeregisterScalableTargetRequest; import com.amazonaws.services.applicationautoscaling.model.DescribeScalableTargetsRequest; import com.amazonaws.services.applicationautoscaling.model.DescribeScalableTargetsResult; import com.amazonaws.services.applicationautoscaling.model.DescribeScalingPoliciesRequest; import com.amazonaws.services.applicationautoscaling.model.DescribeScalingPoliciesResult; import com.amazonaws.services.applicationautoscaling.model.ScalableDimension; import com.amazonaws.services.applicationautoscaling.model.ServiceNamespace; public class DisableDynamoDBAutoscaling { static AWSApplicationAutoScalingClient aaClient = new AWSApplicationAutoScalingClient(); public static void main(String args[]) { ServiceNamespace ns = ServiceNamespace.Dynamodb; ScalableDimension tableWCUs = ScalableDimension.DynamodbTableWriteCapacityUnits; String resourceID = "table/TestTable"; // Delete the scaling policy DeleteScalingPolicyRequest delSPRequest = new DeleteScalingPolicyRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceId(resourceID) .withPolicyName("MyScalingPolicy"); try { aaClient.deleteScalingPolicy(delSPRequest); } catch (Exception e) { System.err.println("Unable to delete scaling policy: "); System.err.println(e.getMessage()); } // Verify that the scaling policy was deleted DescribeScalingPoliciesRequest descSPRequest = new DescribeScalingPoliciesRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceId(resourceID); try { DescribeScalingPoliciesResult dspResult = aaClient.describeScalingPolicies(descSPRequest); System.out.println("DescribeScalingPolicies result: "); System.out.println(dspResult); } catch (Exception e) { e.printStackTrace(); System.err.println("Unable to describe scaling policy: "); System.err.println(e.getMessage()); } System.out.println(); // Remove the scalable target DeregisterScalableTargetRequest delSTRequest = new DeregisterScalableTargetRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceId(resourceID); try { aaClient.deregisterScalableTarget(delSTRequest); } catch (Exception e) { System.err.println("Unable to deregister scalable target: "); System.err.println(e.getMessage()); } // Verify that the scalable target was removed DescribeScalableTargetsRequest dscRequest = new DescribeScalableTargetsRequest() .withServiceNamespace(ns) .withScalableDimension(tableWCUs) .withResourceIds(resourceID); try { DescribeScalableTargetsResult dsaResult = aaClient.describeScalableTargets(dscRequest); System.out.println("DescribeScalableTargets result: "); System.out.println(dsaResult); System.out.println(); } catch (Exception e) { System.err.println("Unable to describe scalable target: "); System.err.println(e.getMessage()); } } }