aws-eks: cluster.addAutoScalingGroupCapacity() does not work as outlined in the docs

[rpivo]

Describe the bug

When attempting to deploy this:

    cluster.addAutoScalingGroupCapacity(
      'my-self-managed-auto-scaling-group',
      {
        instanceType: new InstanceType('t3.small'),
        minCapacity: 1,
        vpcSubnets: { subnetType: SubnetType.PUBLIC },
      },
    )

I receive this error:

The Launch Configuration creation operation is not available in your account. Use launch templates to create configuration templates for your Auto Scaling groups.

The docs don't outright list the launchTemplate option for addAutoScalingGroupCapacity params (this seems like a separate bug), but it is mentioned in other docs on that page. However, if I try:

    const lt = new LaunchTemplate(this, 'my-node-launch-template', {
      machineImage: new EksOptimizedImage(),
      instanceMetadataTags: true,
      instanceType: InstanceType.of(InstanceClass.T3, InstanceSize.SMALL),
      launchTemplateName: 'my-node-group-launch-template',
      userData: userData,
      role: nodeRole,
      securityGroups: [workerSG],
      versionDescription: 'cool stuff,
    })

    cluster.addAutoScalingGroupCapacity(
      'my-self-managed-auto-scaling-group',
      {
        launchTemplate: lt,
      },
    )

I receive this error:

TypeError: Cannot read properties of undefined (reading 'toString')

Regression Issue

• Select this option if this issue appears to be a regression.

Last Known Working CDK Version

unknown

Expected Behavior

N/A

Current Behavior

N/A

Reproduction Steps

N/A

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.180.0

Framework Version

No response

Node.js Version

23

OS

Linux

Language

TypeScript

Language Version

No response

Other information

No response

[rpivo]

I should mention that this:

    cluster.addAutoScalingGroupCapacity(
      'my-self-managed-auto-scaling-group',
      {
        instanceType: new InstanceType('t3.small'),
        minCapacity: 1,
        vpcSubnets: { subnetType: SubnetType.PUBLIC },
      },
    )

Is from the documentation here: https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_eks-readme.html#self-managed-nodes

[pahud]

addAutoScalingGroupCapacity() essentially creates the ASG like this:

aws-cdk/packages/aws-cdk-lib/aws-eks/lib/cluster.ts

Lines 1931 to 1943 in 5eeee75

	const asg = new autoscaling.AutoScalingGroup(this, id, {
	...options,
	vpc: this.vpc,
	machineImage: options.machineImageType === MachineImageType.BOTTLEROCKET ?
	new BottleRocketImage({
	kubernetesVersion: this.version.version,
	}) :
	new EksOptimizedImage({
	nodeType: nodeTypeForInstanceType(options.instanceType),
	cpuArch: cpuArchForInstanceType(options.instanceType),
	kubernetesVersion: this.version.version,
	}),
	});

and AutoScalingGroup() requires this to enable launchTemplate which is missing in addAutoScalingGroupCapacity()

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

Line 1351 in 5eeee75

if (props.launchTemplate || props.mixedInstancesPolicy) {

However, when AUTOSCALING_GENERATE_LAUNCH_TEMPLATE feat flag is enabled, a default launch template should be created for the ASG.

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

Line 1612 in 5eeee75

if (FeatureFlags.of(this).isEnabled(AUTOSCALING_GENERATE_LAUNCH_TEMPLATE)) {

Can you check your cdk.json and see if this feat flag is enabled? If not, please enable it and see if it works for you?

 % grep "generateLaunchTemplateInsteadOfLaunchConfig" cdk.json 
    "@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true,

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[rpivo]

Hey @pahud

@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true

That was exactly what I needed. Thanks!

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