feat(autoscaling): add getter/setter for instance termination protect…

…ion (aws#14308)

Adds getter/setter methods for enabling and querying instance termination protection. This will be used by EC2 Capacity Provider support for ECS to ensure the flag is set correctly when managed termination protection is enabled.

This is a follow up to aws#14283.

----

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

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

@@ -368,7 +368,8 @@ policy](https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-instance-termin
 
 However, you may wish to protect newly-launched instances from being scaled in
 if they are going to run critical applications that should not be prematurely
-terminated. This protection can be removed after launch.
+terminated. EC2 Capacity Providers for Amazon ECS requires this attribute be
+set to `true`.
 
 ```ts
 new autoscaling.AutoScalingGroup(stack, 'ASG', {

packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts

@@ -298,7 +298,7 @@ export interface CommonAutoScalingGroupProps {
    * when scaling in an Auto Scaling Group, subject to the group's termination
    * policy. However, you may wish to protect newly-launched instances from
    * being scaled in if they are going to run critical applications that should
-   * not beß prematurely terminated.
+   * not be prematurely terminated.
    *
    * This flag must be enabled if the Auto Scaling Group will be associated with
    * an ECS Capacity Provider with managed termination protection.
@@ -918,11 +918,15 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
   private readonly groupMetrics: GroupMetrics[] = [];
   private readonly notifications: NotificationConfiguration[] = [];
 
+  protected newInstancesProtectedFromScaleIn?: boolean;
+
   constructor(scope: Construct, id: string, props: AutoScalingGroupProps) {
     super(scope, id, {
       physicalName: props.autoScalingGroupName,
     });
 
+    this.newInstancesProtectedFromScaleIn = props.newInstancesProtectedFromScaleIn;
+
     if (props.initOptions && !props.init) {
       throw new Error('Setting \'initOptions\' requires that \'init\' is also set');
     }
@@ -1038,7 +1042,7 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
       healthCheckType: props.healthCheck && props.healthCheck.type,
       healthCheckGracePeriod: props.healthCheck && props.healthCheck.gracePeriod && props.healthCheck.gracePeriod.toSeconds(),
       maxInstanceLifetime: this.maxInstanceLifetime ? this.maxInstanceLifetime.toSeconds() : undefined,
-      newInstancesProtectedFromScaleIn: props.newInstancesProtectedFromScaleIn,
+      newInstancesProtectedFromScaleIn: Lazy.any({ produce: () => this.newInstancesProtectedFromScaleIn }),
     };
 
     if (!hasPublic && props.associatePublicIpAddress) {
@@ -1144,6 +1148,20 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
     });
   }
 
+  /**
+   * Ensures newly-launched instances are protected from scale-in.
+   */
+  public protectNewInstancesFromScaleIn() {
+    this.newInstancesProtectedFromScaleIn = true;
+  }
+
+  /**
+   * Returns `true` if newly-launched instances are protected from scale-in.
+   */
+  public areNewInstancesProtectedFromScaleIn(): boolean {
+    return this.newInstancesProtectedFromScaleIn === true;
+  }
+
   /**
    * Apply CloudFormation update policies for the AutoScalingGroup
    */

packages/@aws-cdk/aws-autoscaling/test/auto-scaling-group.test.ts

@@ -1314,6 +1314,50 @@ nodeunitShim({
     test.deepEqual(Object.values(autoscaling.ScalingEvent).length - 1, autoscaling.ScalingEvents.ALL._types.length);
     test.done();
   },
+
+  'Can protect new instances from scale-in via constructor property'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const vpc = mockVpc(stack);
+
+    // WHEN
+    const asg = new autoscaling.AutoScalingGroup(stack, 'MyASG', {
+      instanceType: ec2.InstanceType.of(ec2.InstanceClass.M4, ec2.InstanceSize.MICRO),
+      machineImage: new ec2.AmazonLinuxImage(),
+      vpc,
+      newInstancesProtectedFromScaleIn: true,
+    });
+
+    // THEN
+    test.strictEqual(asg.areNewInstancesProtectedFromScaleIn(), true);
+    expect(stack).to(haveResourceLike('AWS::AutoScaling::AutoScalingGroup', {
+      NewInstancesProtectedFromScaleIn: true,
+    }));
+
+    test.done();
+  },
+
+  'Can protect new instances from scale-in via setter'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const vpc = mockVpc(stack);
+
+    // WHEN
+    const asg = new autoscaling.AutoScalingGroup(stack, 'MyASG', {
+      instanceType: ec2.InstanceType.of(ec2.InstanceClass.M4, ec2.InstanceSize.MICRO),
+      machineImage: new ec2.AmazonLinuxImage(),
+      vpc,
+    });
+    asg.protectNewInstancesFromScaleIn();
+
+    // THEN
+    test.strictEqual(asg.areNewInstancesProtectedFromScaleIn(), true);
+    expect(stack).to(haveResourceLike('AWS::AutoScaling::AutoScalingGroup', {
+      NewInstancesProtectedFromScaleIn: true,
+    }));
+
+    test.done();
+  },
 });
 
 function mockVpc(stack: cdk.Stack) {
@@ -1345,25 +1389,6 @@ test('Can set autoScalingGroupName', () => {
   }));
 });
 
-test('Can protect new instances from scale-in', () => {
-  // GIVEN
-  const stack = new cdk.Stack();
-  const vpc = mockVpc(stack);
-
-  // WHEN
-  new autoscaling.AutoScalingGroup(stack, 'MyASG', {
-    instanceType: ec2.InstanceType.of(ec2.InstanceClass.M4, ec2.InstanceSize.MICRO),
-    machineImage: new ec2.AmazonLinuxImage(),
-    vpc,
-    newInstancesProtectedFromScaleIn: true,
-  });
-
-  // THEN
-  expect(stack).to(haveResourceLike('AWS::AutoScaling::AutoScalingGroup', {
-    NewInstancesProtectedFromScaleIn: true,
-  }));
-});
-
 test('can use Vpc imported from unparseable list tokens', () => {
   // GIVEN
   const stack = new cdk.Stack();