feat(applicationautoscaling): add PredefinedMetric for Lambda provisioned concurrency autoscaling (#6394)

feat(applicationautoscaling): add PredefinedMetric for Lambda provisioned concurrency autoscaling (#6394  )

Closes #6369

Author: pahud

packages/@aws-cdk/aws-applicationautoscaling/README.md

@@ -157,3 +157,42 @@ capacity.scaleOnSchedule('AllowDownscalingAtNight', {
   schedule: autoscaling.Schedule.cron({ hour: '20', minute: '0' }),
   minCapacity: 1
 });
+```
+
+## Examples
+
+### Lambda Provisioned Concurrency Auto Scaling
+
+```ts
+   const handler = new lambda.Function(this, 'MyFunction', {
+      runtime: lambda.Runtime.PYTHON_3_7,
+      handler: 'index.handler',
+      code: new lambda.InlineCode(`
+import json, time
+def handler(event, context):
+    time.sleep(1)
+    return {
+        'statusCode': 200,
+        'body': json.dumps('Hello CDK from Lambda!')
+    }`),
+      reservedConcurrentExecutions: 2,
+    });
+    
+    const fnVer = handler.addVersion('CDKLambdaVersion', undefined, 'demo alias', 10);
+
+    new apigateway.LambdaRestApi(this, 'API', { handler: fnVer })
+
+    const target = new applicationautoscaling.ScalableTarget(this, 'ScalableTarget', {
+      serviceNamespace: applicationautoscaling.ServiceNamespace.LAMBDA,
+      maxCapacity: 100,
+      minCapacity: 10,
+      resourceId: `function:${handler.functionName}:${fnVer.version}`,
+      scalableDimension: 'lambda:function:ProvisionedConcurrency',
+    })
+s
+    target.scaleToTrackMetric('PceTracking', {
+      targetValue: 0.9,
+      predefinedMetric: applicationautoscaling.PredefinedMetric.LAMBDA_PROVISIONED_CONCURRENCY_UTILIZATION,
+    })
+  }
+  ```

packages/@aws-cdk/aws-applicationautoscaling/lib/target-tracking-scaling-policy.ts

@@ -173,15 +173,64 @@ function renderCustomMetric(metric?: cloudwatch.IMetric): CfnScalingPolicy.Custo
  * One of the predefined autoscaling metrics
  */
 export enum PredefinedMetric {
+ /**
+  * DYNAMODB_READ_CAPACITY_UTILIZATIO
+  * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+  */
   DYNAMODB_READ_CAPACITY_UTILIZATION = 'DynamoDBReadCapacityUtilization',
+ /**
+  * DYANMODB_WRITE_CAPACITY_UTILIZATION
+  * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+  */
   DYANMODB_WRITE_CAPACITY_UTILIZATION = 'DynamoDBWriteCapacityUtilization',
+  /**
+   * ALB_REQUEST_COUNT_PER_TARGET
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   ALB_REQUEST_COUNT_PER_TARGET = 'ALBRequestCountPerTarget',
+  /**
+   * RDS_READER_AVERAGE_CPU_UTILIZATION
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   RDS_READER_AVERAGE_CPU_UTILIZATION = 'RDSReaderAverageCPUUtilization',
+  /**
+   * RDS_READER_AVERAGE_DATABASE_CONNECTIONS
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   RDS_READER_AVERAGE_DATABASE_CONNECTIONS = 'RDSReaderAverageDatabaseConnections',
+  /**
+   * EC2_SPOT_FLEET_REQUEST_AVERAGE_CPU_UTILIZATION
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   EC2_SPOT_FLEET_REQUEST_AVERAGE_CPU_UTILIZATION = 'EC2SpotFleetRequestAverageCPUUtilization',
+  /**
+   * EC2_SPOT_FLEET_REQUEST_AVERAGE_NETWORK_IN
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   EC2_SPOT_FLEET_REQUEST_AVERAGE_NETWORK_IN = 'EC2SpotFleetRequestAverageNetworkIn',
+  /**
+   * EC2_SPOT_FLEET_REQUEST_AVERAGE_NETWORK_OUT
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   EC2_SPOT_FLEET_REQUEST_AVERAGE_NETWORK_OUT = 'EC2SpotFleetRequestAverageNetworkOut',
+  /**
+   * SAGEMAKER_VARIANT_INVOCATIONS_PER_INSTANCE
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   SAGEMAKER_VARIANT_INVOCATIONS_PER_INSTANCE = 'SageMakerVariantInvocationsPerInstance',
+  /**
+   * ECS_SERVICE_AVERAGE_CPU_UTILIZATION
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   ECS_SERVICE_AVERAGE_CPU_UTILIZATION = 'ECSServiceAverageCPUUtilization',
+  /**
+   * ECS_SERVICE_AVERAGE_CPU_UTILIZATION
+   * @see https://docs.aws.amazon.com/autoscaling/application/APIReference/API_PredefinedMetricSpecification.html
+   */
   ECS_SERVICE_AVERAGE_MEMORY_UTILIZATION = 'ECSServiceAverageMemoryUtilization',
+  /**
+   * LAMBDA_PROVISIONED_CONCURRENCY_UTILIZATION
+   * @see https://docs.aws.amazon.com/lambda/latest/dg/monitoring-metrics.html#monitoring-metrics-concurrency
+   */
+  LAMBDA_PROVISIONED_CONCURRENCY_UTILIZATION = "LambdaProvisionedConcurrencyUtilization",
 }

packages/@aws-cdk/aws-applicationautoscaling/test/test.target-tracking.ts

@@ -30,6 +30,30 @@ export = {
     test.done();
   },
 
+  'test setup target tracking on predefined metric for lambda'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const target = createScalableTarget(stack);
+
+    // WHEN
+    target.scaleToTrackMetric('Tracking', {
+      predefinedMetric: appscaling.PredefinedMetric.LAMBDA_PROVISIONED_CONCURRENCY_UTILIZATION,
+      targetValue: 0.9,
+    });
+
+    // THEN
+    expect(stack).to(haveResource('AWS::ApplicationAutoScaling::ScalingPolicy', {
+      PolicyType: "TargetTrackingScaling",
+      TargetTrackingScalingPolicyConfiguration: {
+        PredefinedMetricSpecification: { PredefinedMetricType: "LambdaProvisionedConcurrencyUtilization" },
+        TargetValue: 0.9
+      }
+
+    }));
+
+    test.done();
+  },
+
   'test setup target tracking on custom metric'(test: Test) {
     // GIVEN
     const stack = new cdk.Stack();