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Oltre a utilizzare AWS Management Console and the AWS Command Line Interface (AWS CLI), puoi scrivere applicazioni che interagiscono con la scalabilità automatica di Amazon DynamoDB. Questa sezione contiene due programmi Java che puoi utilizzare per verificare questa funzionalità:
-
EnableDynamoDBAutoscaling.java -
DisableDynamoDBAutoscaling.java
Abilitazione di Application Auto Scaling per una tabella
Nel programma seguente viene riportato un esempio di configurazione di una policy di scalabilità automatica per una tabella DynamoDB (TestTable). Si procede nel seguente modo.
-
Il programma registra unità di capacità in scrittura come un obiettivo scalabile per
TestTable. L'intervallo per questo parametro è compreso tra 5 e 10 unità di capacità di scrittura. -
Dopo aver creato l'obiettivo scalabile, il programma sviluppa configurazioni di monitoraggio obiettivi. La policy cerca di mantenere un rapporto obiettivo del 50% tra capacità di scrittura utilizzata e capacità di scrittura assegnata.
-
In seguito, il programma crea la policy di dimensionamento in base alla configurazione di monitoraggio obiettivi.
Nota
Quando rimuovi manualmente una tabella o una replica globale di una tabella, non rimuovi automaticamente gli obiettivi scalabili, le politiche di scalabilità o gli allarmi associati. CloudWatch
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.applicationautoscaling.ApplicationAutoScalingClient;
import software.amazon.awssdk.services.applicationautoscaling.model.ApplicationAutoScalingException;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalableTargetsRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalableTargetsResponse;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalingPoliciesRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalingPoliciesResponse;
import software.amazon.awssdk.services.applicationautoscaling.model.PolicyType;
import software.amazon.awssdk.services.applicationautoscaling.model.PredefinedMetricSpecification;
import software.amazon.awssdk.services.applicationautoscaling.model.PutScalingPolicyRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.RegisterScalableTargetRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.ScalingPolicy;
import software.amazon.awssdk.services.applicationautoscaling.model.ServiceNamespace;
import software.amazon.awssdk.services.applicationautoscaling.model.ScalableDimension;
import software.amazon.awssdk.services.applicationautoscaling.model.MetricType;
import software.amazon.awssdk.services.applicationautoscaling.model.TargetTrackingScalingPolicyConfiguration;
import java.util.List;
/**
* Before running this Java V2 code example, set up your development environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class EnableDynamoDBAutoscaling {
public static void main(String[] args) {
final String usage = """
Usage:
<tableId> <roleARN> <policyName>\s
Where:
tableId - The table Id value (for example, table/Music).
roleARN - The ARN of the role that has ApplicationAutoScaling permissions.
policyName - The name of the policy to create.
""";
if (args.length != 3) {
System.out.println(usage);
System.exit(1);
}
System.out.println("This example registers an Amazon DynamoDB table, which is the resource to scale.");
String tableId = args[0];
String roleARN = args[1];
String policyName = args[2];
ServiceNamespace ns = ServiceNamespace.DYNAMODB;
ScalableDimension tableWCUs = ScalableDimension.DYNAMODB_TABLE_WRITE_CAPACITY_UNITS;
ApplicationAutoScalingClient appAutoScalingClient = ApplicationAutoScalingClient.builder()
.region(Region.US_EAST_1)
.build();
registerScalableTarget(appAutoScalingClient, tableId, roleARN, ns, tableWCUs);
verifyTarget(appAutoScalingClient, tableId, ns, tableWCUs);
configureScalingPolicy(appAutoScalingClient, tableId, ns, tableWCUs, policyName);
}
public static void registerScalableTarget(ApplicationAutoScalingClient appAutoScalingClient, String tableId, String roleARN, ServiceNamespace ns, ScalableDimension tableWCUs) {
try {
RegisterScalableTargetRequest targetRequest = RegisterScalableTargetRequest.builder()
.serviceNamespace(ns)
.scalableDimension(tableWCUs)
.resourceId(tableId)
.roleARN(roleARN)
.minCapacity(5)
.maxCapacity(10)
.build();
appAutoScalingClient.registerScalableTarget(targetRequest);
System.out.println("You have registered " + tableId);
} catch (ApplicationAutoScalingException e) {
System.err.println(e.awsErrorDetails().errorMessage());
}
}
// Verify that the target was created.
public static void verifyTarget(ApplicationAutoScalingClient appAutoScalingClient, String tableId, ServiceNamespace ns, ScalableDimension tableWCUs) {
DescribeScalableTargetsRequest dscRequest = DescribeScalableTargetsRequest.builder()
.scalableDimension(tableWCUs)
.serviceNamespace(ns)
.resourceIds(tableId)
.build();
DescribeScalableTargetsResponse response = appAutoScalingClient.describeScalableTargets(dscRequest);
System.out.println("DescribeScalableTargets result: ");
System.out.println(response);
}
// Configure a scaling policy.
public static void configureScalingPolicy(ApplicationAutoScalingClient appAutoScalingClient, String tableId, ServiceNamespace ns, ScalableDimension tableWCUs, String policyName) {
// Check if the policy exists before creating a new one.
DescribeScalingPoliciesResponse describeScalingPoliciesResponse = appAutoScalingClient.describeScalingPolicies(DescribeScalingPoliciesRequest.builder()
.serviceNamespace(ns)
.resourceId(tableId)
.scalableDimension(tableWCUs)
.build());
if (!describeScalingPoliciesResponse.scalingPolicies().isEmpty()) {
// If policies exist, consider updating an existing policy instead of creating a new one.
System.out.println("Policy already exists. Consider updating it instead.");
List<ScalingPolicy> polList = describeScalingPoliciesResponse.scalingPolicies();
for (ScalingPolicy pol : polList) {
System.out.println("Policy name:" +pol.policyName());
}
} else {
// If no policies exist, proceed with creating a new policy.
PredefinedMetricSpecification specification = PredefinedMetricSpecification.builder()
.predefinedMetricType(MetricType.DYNAMO_DB_WRITE_CAPACITY_UTILIZATION)
.build();
TargetTrackingScalingPolicyConfiguration policyConfiguration = TargetTrackingScalingPolicyConfiguration.builder()
.predefinedMetricSpecification(specification)
.targetValue(50.0)
.scaleInCooldown(60)
.scaleOutCooldown(60)
.build();
PutScalingPolicyRequest putScalingPolicyRequest = PutScalingPolicyRequest.builder()
.targetTrackingScalingPolicyConfiguration(policyConfiguration)
.serviceNamespace(ns)
.scalableDimension(tableWCUs)
.resourceId(tableId)
.policyName(policyName)
.policyType(PolicyType.TARGET_TRACKING_SCALING)
.build();
try {
appAutoScalingClient.putScalingPolicy(putScalingPolicyRequest);
System.out.println("You have successfully created a scaling policy for an Application Auto Scaling scalable target");
} catch (ApplicationAutoScalingException e) {
System.err.println("Error: " + e.awsErrorDetails().errorMessage());
}
}
}
}
Disabilitazione di Application Auto Scaling per una tabella
Nel programma seguente, il processo precedente viene invertito. Esso rimuove la policy di scalabilità automatica e annulla la registrazione dell'obiettivo scalabile.
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.applicationautoscaling.ApplicationAutoScalingClient;
import software.amazon.awssdk.services.applicationautoscaling.model.ApplicationAutoScalingException;
import software.amazon.awssdk.services.applicationautoscaling.model.DeleteScalingPolicyRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DeregisterScalableTargetRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalableTargetsRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalableTargetsResponse;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalingPoliciesRequest;
import software.amazon.awssdk.services.applicationautoscaling.model.DescribeScalingPoliciesResponse;
import software.amazon.awssdk.services.applicationautoscaling.model.ScalableDimension;
import software.amazon.awssdk.services.applicationautoscaling.model.ServiceNamespace;
/**
* Before running this Java V2 code example, set up your development environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
*/
public class DisableDynamoDBAutoscaling {
public static void main(String[] args) {
final String usage = """
Usage:
<tableId> <policyName>\s
Where:
tableId - The table Id value (for example, table/Music).\s
policyName - The name of the policy (for example, $Music5-scaling-policy).
""";
if (args.length != 2) {
System.out.println(usage);
System.exit(1);
}
ApplicationAutoScalingClient appAutoScalingClient = ApplicationAutoScalingClient.builder()
.region(Region.US_EAST_1)
.build();
ServiceNamespace ns = ServiceNamespace.DYNAMODB;
ScalableDimension tableWCUs = ScalableDimension.DYNAMODB_TABLE_WRITE_CAPACITY_UNITS;
String tableId = args[0];
String policyName = args[1];
deletePolicy(appAutoScalingClient, policyName, tableWCUs, ns, tableId);
verifyScalingPolicies(appAutoScalingClient, tableId, ns, tableWCUs);
deregisterScalableTarget(appAutoScalingClient, tableId, ns, tableWCUs);
verifyTarget(appAutoScalingClient, tableId, ns, tableWCUs);
}
public static void deletePolicy(ApplicationAutoScalingClient appAutoScalingClient, String policyName, ScalableDimension tableWCUs, ServiceNamespace ns, String tableId) {
try {
DeleteScalingPolicyRequest delSPRequest = DeleteScalingPolicyRequest.builder()
.policyName(policyName)
.scalableDimension(tableWCUs)
.serviceNamespace(ns)
.resourceId(tableId)
.build();
appAutoScalingClient.deleteScalingPolicy(delSPRequest);
System.out.println(policyName +" was deleted successfully.");
} catch (ApplicationAutoScalingException e) {
System.err.println(e.awsErrorDetails().errorMessage());
}
}
// Verify that the scaling policy was deleted
public static void verifyScalingPolicies(ApplicationAutoScalingClient appAutoScalingClient, String tableId, ServiceNamespace ns, ScalableDimension tableWCUs) {
DescribeScalingPoliciesRequest dscRequest = DescribeScalingPoliciesRequest.builder()
.scalableDimension(tableWCUs)
.serviceNamespace(ns)
.resourceId(tableId)
.build();
DescribeScalingPoliciesResponse response = appAutoScalingClient.describeScalingPolicies(dscRequest);
System.out.println("DescribeScalableTargets result: ");
System.out.println(response);
}
public static void deregisterScalableTarget(ApplicationAutoScalingClient appAutoScalingClient, String tableId, ServiceNamespace ns, ScalableDimension tableWCUs) {
try {
DeregisterScalableTargetRequest targetRequest = DeregisterScalableTargetRequest.builder()
.scalableDimension(tableWCUs)
.serviceNamespace(ns)
.resourceId(tableId)
.build();
appAutoScalingClient.deregisterScalableTarget(targetRequest);
System.out.println("The scalable target was deregistered.");
} catch (ApplicationAutoScalingException e) {
System.err.println(e.awsErrorDetails().errorMessage());
}
}
public static void verifyTarget(ApplicationAutoScalingClient appAutoScalingClient, String tableId, ServiceNamespace ns, ScalableDimension tableWCUs) {
DescribeScalableTargetsRequest dscRequest = DescribeScalableTargetsRequest.builder()
.scalableDimension(tableWCUs)
.serviceNamespace(ns)
.resourceIds(tableId)
.build();
DescribeScalableTargetsResponse response = appAutoScalingClient.describeScalableTargets(dscRequest);
System.out.println("DescribeScalableTargets result: ");
System.out.println(response);
}
}
