Describe the bug

As of August 2025, Amazon OpenSearch Service now supports I8g instances which use local NVMe storage instead of EBS. However, the CDK construct for an OpenSearch Domain has not been updated to account for such.

Regression Issue

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

Last Known Working CDK Library Version

No response

Expected Behavior

Expect to be able to use CDK to define an OpenSearch Domain with I8g instances as data nodes (not using EBS)

If EBS is not disabled, I would expect validation to fail similar to for I4g

ValidationError: I3, R6GD, I4G, I4I, IM4GN and R7GD instance types do not support EBS storage volumes.

Current Behavior

When disabling EBS, the construct fails to initialize with a validation error

ValidationError: EBS volumes are required when using instance types other than R3, I3, R6GD, I4G, I4I, IM4GN or R7GD.

When not disabling EBS, I think CloudFormation deployment fails?

Reproduction Steps

Attempt to create a domain using I8g instances for the data nodes and EBS disabled

class OpensearchSandboxStack extends Stack {
	constructor(scope: Construct, id: string) {
		super(scope, id);

		new Domain(this, "MyDomain", {
			version: EngineVersion.OPENSEARCH_2_19,
			ebs: { enabled: false },
			capacity: {
				dataNodeInstanceType: "i8g.4xlarge.search",
			},
		});
	}
}

Possible Solution

Update unSupportEbsInstanceType to include InstanceClass.I8g

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

2.215.0

AWS CDK CLI version

2.1029.4

Node.js Version

N/A

OS

N/A

Language

TypeScript

Language Version

No response

Other information

No response