From bd10ce045cc3b7f7537651ca4f3efb08033c8cbc Mon Sep 17 00:00:00 2001
From: Clay Rosenthal <clayros@amazon.com>
Date: Mon, 10 Mar 2025 14:24:45 -0700
Subject: [PATCH] feat(ec2): Adding placementGroup prop to LaunchTemplate

Signed-off-by: Clay Rosenthal <clayros@amazon.com>
---
 .../aws-ec2/lib/launch-template.ts            | 14 +++++-
 .../aws-ec2/test/launch-template.test.ts      | 47 +++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/packages/aws-cdk-lib/aws-ec2/lib/launch-template.ts b/packages/aws-cdk-lib/aws-ec2/lib/launch-template.ts
index 756cda646ce35..f7d0a76029d53 100644
--- a/packages/aws-cdk-lib/aws-ec2/lib/launch-template.ts
+++ b/packages/aws-cdk-lib/aws-ec2/lib/launch-template.ts
@@ -4,6 +4,7 @@ import { CfnLaunchTemplate } from './ec2.generated';
 import { InstanceType } from './instance-types';
 import { IKeyPair } from './key-pair';
 import { IMachineImage, MachineImageConfig, OperatingSystemType } from './machine-image';
+import { IPlacementGroup } from './placement-group';
 import { launchTemplateBlockDeviceMappings } from './private/ebs-util';
 import { ISecurityGroup } from './security-group';
 import { UserData } from './user-data';
@@ -441,6 +442,13 @@ export interface LaunchTemplateProps {
    * @default - No instance profile
    */
   readonly instanceProfile?: iam.IInstanceProfile;
+
+  /**
+   * The placement group that you want to launch the instance into.
+   *
+   * @default - no placement group will be used for this launch template.
+   */
+  readonly placementGroup?: IPlacementGroup;
 }
 
 /**
@@ -783,6 +791,9 @@ export class LaunchTemplate extends Resource implements ILaunchTemplate, iam.IGr
         userData: userDataToken,
         metadataOptions: this.renderMetadataOptions(props),
         networkInterfaces,
+        placement: props.placementGroup ? {
+          groupName: props.placementGroup.placementGroupName,
+        } : undefined,
 
         // Fields not yet implemented:
         // ==========================
@@ -811,7 +822,8 @@ export class LaunchTemplate extends Resource implements ILaunchTemplate, iam.IGr
         // Should be implemented via the Tagging aspect in CDK core. Complication will be that this tagging interface is very unique to LaunchTemplates.
         // tagSpecification: undefined
 
-        // CDK has no abstraction for Placement yet.
+        // CDK only has placement groups, not placement.
+        // Specifiying options other than placementGroup is not supported yet.
         // placement: undefined,
 
       },
diff --git a/packages/aws-cdk-lib/aws-ec2/test/launch-template.test.ts b/packages/aws-cdk-lib/aws-ec2/test/launch-template.test.ts
index d277cdaaf1bbc..5807388493a7b 100644
--- a/packages/aws-cdk-lib/aws-ec2/test/launch-template.test.ts
+++ b/packages/aws-cdk-lib/aws-ec2/test/launch-template.test.ts
@@ -28,6 +28,8 @@ import {
   LaunchTemplate,
   LaunchTemplateHttpTokens,
   OperatingSystemType,
+  PlacementGroup,
+  PlacementGroupStrategy,
   SecurityGroup,
   SpotInstanceInterruption,
   SpotRequestType,
@@ -889,6 +891,51 @@ describe('LaunchTemplate', () => {
       },
     });
   });
+
+  test('Given placementGroup', () => {
+    // GIVEN
+    const pg = new PlacementGroup(stack, 'PlacementGroup', {
+      strategy: PlacementGroupStrategy.CLUSTER,
+    });
+
+    // WHEN
+    new LaunchTemplate(stack, 'Template', {
+      placementGroup: pg,
+    });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::EC2::LaunchTemplate', {
+      LaunchTemplateData: {
+        Placement: {
+          GroupName: {
+            'Fn::GetAtt': [
+              'PlacementGroup68E91A0F',
+              'GroupName',
+            ],
+          },
+        },
+      },
+    });
+  });
+
+  test('Given imported placementGroup', () => {
+    // GIVEN
+    const importedPg = PlacementGroup.fromPlacementGroupName(stack, 'ImportedPlacementGroup', 'my-placement-group');
+
+    // WHEN
+    new LaunchTemplate(stack, 'Template', {
+      placementGroup: importedPg,
+    });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::EC2::LaunchTemplate', {
+      LaunchTemplateData: {
+        Placement: {
+          GroupName: 'my-placement-group',
+        },
+      },
+    });
+  });
 });
 
 describe('LaunchTemplate marketOptions', () => {