From 9a98ae6831caa948549df6587604b6dc66bbe019 Mon Sep 17 00:00:00 2001
From: Michael Fischer <fiscmi@amazon.com>
Date: Tue, 20 Apr 2021 15:07:23 -0700
Subject: [PATCH] feat(aws-autoscaling): add support for
 NewInstancesProtectedFromScaleIn

---
 packages/@aws-cdk/aws-autoscaling/README.md   | 17 +++++++++++++++++
 .../aws-autoscaling/lib/auto-scaling-group.ts | 18 ++++++++++++++++++
 .../test/auto-scaling-group.test.ts           | 19 +++++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/packages/@aws-cdk/aws-autoscaling/README.md b/packages/@aws-cdk/aws-autoscaling/README.md
index 95e1a25963afe..b0711c78062c4 100644
--- a/packages/@aws-cdk/aws-autoscaling/README.md
+++ b/packages/@aws-cdk/aws-autoscaling/README.md
@@ -360,6 +360,23 @@ new autoscaling.AutoScalingGroup(stack, 'ASG', {
 });
 ```
 
+## Protecting new instances from being terminated on scale-in
+
+By default, Auto Scaling can terminate an instance at any time after launch when
+scaling in an Auto Scaling Group, subject to the group's [termination
+policy](https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-instance-termination.html).
+
+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.
+
+```ts
+new autoscaling.AutoScalingGroup(stack, 'ASG', {
+  newInstancesProtectedFromScaleIn: true,
+  // ...
+});
+```
+
 ## Future work
 
 * [ ] CloudWatch Events (impossible to add currently as the AutoScalingGroup ARN is
diff --git a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
index 42ea38ab80d11..c72a0d6a760b0 100644
--- a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
+++ b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
@@ -290,6 +290,23 @@ export interface CommonAutoScalingGroupProps {
    */
   readonly updatePolicy?: UpdatePolicy;
 
+  /**
+   * Whether newly-launched instances are protected from termination by Amazon
+   * EC2 Auto Scaling when scaling in.
+   *
+   * By default, Auto Scaling can terminate an instance at any time after launch
+   * 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.
+   *
+   * This flag must be enabled if the Auto Scaling Group will be associated with
+   * an ECS Capacity Provider with managed termination protection.
+   *
+   * @default false
+   */
+  readonly newInstancesProtectedFromScaleIn?: boolean;
+
   /**
    * The name of the Auto Scaling group. This name must be unique per Region per account.
    * @default - Auto generated by CloudFormation
@@ -1021,6 +1038,7 @@ 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,
     };
 
     if (!hasPublic && props.associatePublicIpAddress) {
diff --git a/packages/@aws-cdk/aws-autoscaling/test/auto-scaling-group.test.ts b/packages/@aws-cdk/aws-autoscaling/test/auto-scaling-group.test.ts
index 55e69dbb46eda..670b44b03212c 100644
--- a/packages/@aws-cdk/aws-autoscaling/test/auto-scaling-group.test.ts
+++ b/packages/@aws-cdk/aws-autoscaling/test/auto-scaling-group.test.ts
@@ -1351,6 +1351,25 @@ 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', {
+    NewResourcesProtectedFromScaleIn: true,
+  }));
+});
+
 test('can use Vpc imported from unparseable list tokens', () => {
   // GIVEN
   const stack = new cdk.Stack();