Describe the bug

I'm attempting to create an EC2 ECS compute environment using the AWS Batch constructs that makes use of only Graviton instances. When I deploy the stack I get the following error:

Error executing request, Exception : arm-based instance type cannot be used with other instance types.

Regression Issue

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

Last Known Working CDK Version

No response

Expected Behavior

When encountering a know arm-based instance class, the construct should not append optimal as it's not supported for arm based instances

Current Behavior

When deploying a EC2 ECS Compute Environment, the error below is thrown.

14:57:17 | CREATE_FAILED        | AWS::Batch::ComputeEnvironment | MyECSComputeEnvironment6A03089C
Resource handler returned message: "Error executing request, Exception : arm-based instance type cannot be used with other instance types., RequestId: 167a0e5
f-0376-4ad4-a0b6-34a85a940cb7 (Service: Batch, Status Code: 400, Request ID: 167a0e5f-0376-4ad4-a0b6-34a85a940cb7)" (RequestToken: d266edf5-f5cd-d61f-866f-5e5
ecefa478c, HandlerErrorCode: InvalidRequest)

Reproduction Steps

I'm declaring my compute environment as follows:

const computeEnvironment = new ManagedEc2EcsComputeEnvironment(this, 'MyECSComputeEnvironment', {
    vpc,
    minvCpus: 0,
    maxvCpus: 8,
    instanceClasses: [InstanceClass.M6G],
})

When deploying there is an error:

14:57:17 | CREATE_FAILED        | AWS::Batch::ComputeEnvironment | MyECSComputeEnvironment6A03089C
Resource handler returned message: "Error executing request, Exception : arm-based instance type cannot be used with other instance types., RequestId: 167a0e5
f-0376-4ad4-a0b6-34a85a940cb7 (Service: Batch, Status Code: 400, Request ID: 167a0e5f-0376-4ad4-a0b6-34a85a940cb7)" (RequestToken: d266edf5-f5cd-d61f-866f-5e5
ecefa478c, HandlerErrorCode: InvalidRequest)

Possible Solution

When I inspect the synthesized CloudFormation Stack I can see that optimal has been appended to the InstanceTypes list:

Possible solution would be to fix logic in renderInstances to take into account the types of instances (Arm vs AMD).

Additional Information/Context

Workaround

I've found workaround by setting the useOptimalInstanceClasses to false but this is not expected behavior because I've explicitly set the types of instances I want.

const computeEnvironment = new ManagedEc2EcsComputeEnvironment(this, 'MyECSComputeEnvironment', {
    vpc,
    minvCpus: 0,
    maxvCpus: 8,
    instanceClasses: [InstanceClass.M6G],
    useOptimalInstanceClasses: false
})

CDK CLI Version

2.152.0 (build faa7d79)

Framework Version

No response

Node.js Version

v20.14.0

OS

ubuntu

Language

TypeScript

Language Version

No response

Other information

No response