chore(ecs-service-extensions): Deprecate scale on CPU utilization extension (#17802)

----
This PR deprecates one of the existing `scaleOnCpuUtilization` extension. We recommend users to configure task auto scaling using the [`autoScaleTaskCount`](https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk-containers/ecs-service-extensions/lib/service.ts#L61) in the `Service` construct. 

Related PR: #17101 

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: upparekh

packages/@aws-cdk-containers/ecs-service-extensions/lib/extensions/scale-on-cpu-utilization.ts

@@ -2,8 +2,13 @@ import * as ecs from '@aws-cdk/aws-ecs';
 import * as cdk from '@aws-cdk/core';
 import { ServiceExtension, ServiceBuild } from './extension-interfaces';
 
+
 /**
  * The autoscaling settings.
+ *
+ * @deprecated use the `minTaskCount` and `maxTaskCount` properties of `autoScaleTaskCount` in the `Service` construct
+ * to configure the auto scaling target for the service. For more information, please refer
+ * https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk-containers/ecs-service-extensions/README.md#task-auto-scaling .
  */
 export interface CpuScalingProps {
   /**
@@ -61,6 +66,9 @@ const cpuScalingPropsDefault = {
 
 /**
  * This extension helps you scale your service according to CPU utilization.
+ *
+ * @deprecated To enable target tracking based on CPU utilization, use the `targetCpuUtilization` property of `autoScaleTaskCount` in the `Service` construct.
+ * For more information, please refer https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk-containers/ecs-service-extensions/README.md#task-auto-scaling .
  */
 export class ScaleOnCpuUtilization extends ServiceExtension {
   /**
@@ -126,6 +134,9 @@ export class ScaleOnCpuUtilization extends ServiceExtension {
   // This hook utilizes the resulting service construct
   // once it is created.
   public useService(service: ecs.Ec2Service | ecs.FargateService) {
+    if (this.parentService.scalableTaskCount) {
+      throw Error('Cannot specify \'autoScaleTaskCount\' in the Service construct and also provide a  \'ScaleOnCpuUtilization\' extension. \'ScaleOnCpuUtilization\' is deprecated. Please only provide \'autoScaleTaskCount\'.');
+    }
     const scalingTarget = service.autoScaleTaskCount({
       minCapacity: this.minTaskCount,
       maxCapacity: this.maxTaskCount,
@@ -136,5 +147,6 @@ export class ScaleOnCpuUtilization extends ServiceExtension {
       scaleInCooldown: this.scaleInCooldown,
       scaleOutCooldown: this.scaleOutCooldown,
     });
+    this.parentService.enableAutoScalingPolicy();
   }
 }

packages/@aws-cdk-containers/ecs-service-extensions/lib/service.ts

@@ -221,17 +221,14 @@ export class Service extends Construct {
       }
     }
 
-    // Set desiredCount to `undefined` if auto scaling is configured for the service
-    const desiredCount = props.autoScaleTaskCount ? undefined : (props.desiredCount || 1);
-
     // Give each extension a chance to mutate the service props before
     // service creation
     let serviceProps = {
       cluster: this.cluster,
       taskDefinition: this.taskDefinition,
       minHealthyPercent: 100,
       maxHealthyPercent: 200,
-      desiredCount,
+      desiredCount: props.desiredCount ?? 1,
     } as ServiceBuild;
 
     for (const extensions in this.serviceDescription.extensions) {
@@ -273,6 +270,14 @@ export class Service extends Construct {
       }
     }
 
+    // Set desiredCount to `undefined` if auto scaling is configured for the service
+    if (props.autoScaleTaskCount || this.autoScalingPoliciesEnabled) {
+      serviceProps = {
+        ...serviceProps,
+        desiredCount: undefined,
+      };
+    }
+
     // Now that the service props are determined we can create
     // the service
     if (this.capacityType === EnvironmentCapacityType.EC2) {
@@ -291,17 +296,17 @@ export class Service extends Construct {
       });
 
       if (props.autoScaleTaskCount.targetCpuUtilization) {
-        const targetUtilizationPercent = props.autoScaleTaskCount.targetCpuUtilization;
-        this.scalableTaskCount.scaleOnCpuUtilization(`${this.id}-target-cpu-utilization-${targetUtilizationPercent}`, {
-          targetUtilizationPercent,
+        const targetCpuUtilizationPercent = props.autoScaleTaskCount.targetCpuUtilization;
+        this.scalableTaskCount.scaleOnCpuUtilization(`${this.id}-target-cpu-utilization-${targetCpuUtilizationPercent}`, {
+          targetUtilizationPercent: targetCpuUtilizationPercent,
         });
         this.enableAutoScalingPolicy();
       }
 
       if (props.autoScaleTaskCount.targetMemoryUtilization) {
-        const targetUtilizationPercent = props.autoScaleTaskCount.targetMemoryUtilization;
-        this.scalableTaskCount.scaleOnMemoryUtilization(`${this.id}-target-memory-utilization-${targetUtilizationPercent}`, {
-          targetUtilizationPercent,
+        const targetMemoryUtilizationPercent = props.autoScaleTaskCount.targetMemoryUtilization;
+        this.scalableTaskCount.scaleOnMemoryUtilization(`${this.id}-target-memory-utilization-${targetMemoryUtilizationPercent}`, {
+          targetUtilizationPercent: targetMemoryUtilizationPercent,
         });
         this.enableAutoScalingPolicy();
       }

packages/@aws-cdk-containers/ecs-service-extensions/test/appmesh.test.ts

@@ -2,7 +2,7 @@ import '@aws-cdk/assert-internal/jest';
 import * as appmesh from '@aws-cdk/aws-appmesh';
 import * as ecs from '@aws-cdk/aws-ecs';
 import * as cdk from '@aws-cdk/core';
-import { AppMeshExtension, Container, Environment, ScaleOnCpuUtilization, ServiceDescription, Service } from '../lib';
+import { AppMeshExtension, Container, Environment, ServiceDescription, Service } from '../lib';
 
 describe('appmesh', () => {
   test('should be able to add AWS App Mesh to a service', () => {
@@ -276,9 +276,6 @@ describe('appmesh', () => {
       trafficPort: 80,
       image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
     }));
-    serviceDescription.add(new ScaleOnCpuUtilization({
-      initialTaskCount: 1,
-    }));
 
     const mesh = new appmesh.Mesh(stack, 'my-mesh');
 
@@ -289,6 +286,7 @@ describe('appmesh', () => {
     new Service(stack, 'my-service', {
       environment,
       serviceDescription,
+      desiredCount: 1,
     });
 
     expect(stack).toHaveResourceLike('AWS::ECS::Service', {
@@ -317,9 +315,6 @@ describe('appmesh', () => {
       trafficPort: 80,
       image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
     }));
-    serviceDescription.add(new ScaleOnCpuUtilization({
-      initialTaskCount: 2,
-    }));
 
     const mesh = new appmesh.Mesh(stack, 'my-mesh');
 
@@ -330,6 +325,7 @@ describe('appmesh', () => {
     new Service(stack, 'my-service', {
       environment,
       serviceDescription,
+      desiredCount: 2,
     });
 
     expect(stack).toHaveResourceLike('AWS::ECS::Service', {
@@ -358,9 +354,6 @@ describe('appmesh', () => {
       trafficPort: 80,
       image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
     }));
-    serviceDescription.add(new ScaleOnCpuUtilization({
-      initialTaskCount: 3,
-    }));
 
     const mesh = new appmesh.Mesh(stack, 'my-mesh');
 
@@ -371,6 +364,7 @@ describe('appmesh', () => {
     new Service(stack, 'my-service', {
       environment,
       serviceDescription,
+      desiredCount: 3,
     });
 
     expect(stack).toHaveResourceLike('AWS::ECS::Service', {
@@ -399,9 +393,6 @@ describe('appmesh', () => {
       trafficPort: 80,
       image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
     }));
-    serviceDescription.add(new ScaleOnCpuUtilization({
-      initialTaskCount: 4,
-    }));
 
     const mesh = new appmesh.Mesh(stack, 'my-mesh');
 
@@ -412,6 +403,7 @@ describe('appmesh', () => {
     new Service(stack, 'my-service', {
       environment,
       serviceDescription,
+      desiredCount: 4,
     });
 
     expect(stack).toHaveResourceLike('AWS::ECS::Service', {
@@ -440,9 +432,6 @@ describe('appmesh', () => {
       trafficPort: 80,
       image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
     }));
-    serviceDescription.add(new ScaleOnCpuUtilization({
-      initialTaskCount: 8,
-    }));
 
     const mesh = new appmesh.Mesh(stack, 'my-mesh');
 
@@ -453,6 +442,7 @@ describe('appmesh', () => {
     new Service(stack, 'my-service', {
       environment,
       serviceDescription,
+      desiredCount: 8,
     });
 
     expect(stack).toHaveResourceLike('AWS::ECS::Service', {

packages/@aws-cdk-containers/ecs-service-extensions/test/scale-on-cpu-utilization.test.ts

@@ -149,4 +149,32 @@ describe('scale on cpu utilization', () => {
 
   });
 
+  test('should error if configuring autoscaling target both in the extension and the Service', () => {
+    // GIVEN
+    const stack = new cdk.Stack();
+
+    // WHEN
+    const environment = new Environment(stack, 'production');
+    const serviceDescription = new ServiceDescription();
+
+    serviceDescription.add(new Container({
+      cpu: 256,
+      memoryMiB: 512,
+      trafficPort: 80,
+      image: ecs.ContainerImage.fromRegistry('nathanpeck/name'),
+    }));
+
+    serviceDescription.add(new ScaleOnCpuUtilization());
+    // THEN
+    expect(() => {
+      new Service(stack, 'my-service', {
+        environment,
+        serviceDescription,
+        autoScaleTaskCount: {
+          maxTaskCount: 5,
+        },
+      });
+    }).toThrow('Cannot specify \'autoScaleTaskCount\' in the Service construct and also provide a  \'ScaleOnCpuUtilization\' extension. \'ScaleOnCpuUtilization\' is deprecated. Please only provide \'autoScaleTaskCount\'.');
+  });
+
 });