feat(batch): add AL2023 image types and default to AL2023 (under feature flag) by aws-joelherd · Pull Request #37539 · aws/aws-cdk

aws-joelherd · 2026-04-07T00:22:14Z

Add missing enum values for AWS Batch Ec2Configuration:

EcsMachineImageType.ECS_AL2023_NVIDIA
EksMachineImageType.EKS_AL2023
EksMachineImageType.EKS_AL2023_NVIDIA

Introduce feature flag @aws-cdk/aws-batch:defaultToAL2023 that switches the default imageType from AL2 to AL2023 for both ECS and EKS compute environments. Amazon Linux 2 has reached EOL for EKS (Nov 2025) and reaches EOL for ECS in June 2026.

For EKS compute environments with a launch template, automatically set userdataType to EKS_NODEADM when an AL2023 image type is resolved, as required by the AWS Batch API to ensure nodes join the cluster.

Update A1 instance validation to also reject ECS_AL2023_NVIDIA and to correctly resolve the feature-flag-defaulted imageType.

Issue # (if applicable)

Closes #35839, closes #37205.

Reason for this change

Amazon Linux 2 has reached EOL for EKS (Nov 2025) and reaches EOL for ECS
in June 2026. The AWS Batch service already defaults to AL2023 for newly
created compute environments, but CDK still hardcodes ECS_AL2 / EKS_AL2
when users don't specify an imageType.

Additionally, the ECS_AL2023_NVIDIA, EKS_AL2023, and EKS_AL2023_NVIDIA
image types supported by the Batch API were missing from the CDK enum definitions.

Description of changes

Added EcsMachineImageType.ECS_AL2023_NVIDIA, EksMachineImageType.EKS_AL2023,
and EksMachineImageType.EKS_AL2023_NVIDIA
Introduced feature flag @aws-cdk/aws-batch:defaultToAL2023 that switches the
default imageType from AL2 to AL2023 for both ECS and EKS compute environments
For EKS compute environments with a launch template, automatically sets
userdataType to EKS_NODEADM when an AL2023 image type is resolved, as
required by the AWS Batch API to ensure nodes join the cluster
Updated A1 instance validation to also reject ECS_AL2023_NVIDIA and to
correctly resolve the feature-flag-defaulted imageType

Describe any new or updated permissions being added

None.

Description of how you validated changes

Unit tests cover all new enum values, feature flag on/off for both ECS and EKS,
userdataType behavior with launch templates (including the critical scenario
where the feature flag defaults to AL2023 with a launch template present), and
A1 instance validation. Build passes with 0 errors. 103 batch tests pass,
118 cx-api tests pass.

Checklist

My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

…ure flag) Add missing enum values for AWS Batch Ec2Configuration: - EcsMachineImageType.ECS_AL2023_NVIDIA - EksMachineImageType.EKS_AL2023 - EksMachineImageType.EKS_AL2023_NVIDIA Introduce feature flag `@aws-cdk/aws-batch:defaultToAL2023` that switches the default imageType from AL2 to AL2023 for both ECS and EKS compute environments. Amazon Linux 2 has reached EOL for EKS (Nov 2025) and reaches EOL for ECS in June 2026. For EKS compute environments with a launch template, automatically set `userdataType` to `EKS_NODEADM` when an AL2023 image type is resolved, as required by the AWS Batch API to ensure nodes join the cluster. Update A1 instance validation to also reject ECS_AL2023_NVIDIA and to correctly resolve the feature-flag-defaulted imageType. Closes aws#35839, closes aws#37205

aws-cdk-automation

The pull request linter fails with the following errors:

❌ Features must contain a change to an integration test file and the resulting snapshot.

If you believe this pull request should receive an exemption, please comment and provide a justification. A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed, add Clarification Request to a comment.

✅ A exemption request has been requested. Please wait for a maintainer's review.

aws-joelherd · 2026-04-07T00:28:08Z

The pull request linter fails with the following errors:
❌ Features must contain a change to an integration test file and the resulting snapshot.
If you believe this pull request should receive an exemption, please comment and provide a justification. A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed, add Clarification Request to a comment.

Exemption Request

This change adds new enum values and a feature flag that only affects the default imageType value in the synthesized CloudFormation template. The feature flag is fully covered by unit tests (flag on/off for both ECS and EKS, userdataType with launch templates, A1 validation). The existing integration test for managed compute environments already covers the ECS_AL2023 image type. No new CloudFormation resource types are introduced.

aws-joelherd · 2026-04-07T16:32:38Z

packages/aws-cdk-lib/aws-batch/lib/managed-compute-environment.ts

+   * - ECS_AL2 compatible AMI ids for non-GPU instances, ECS_AL2_NVIDIA compatible AMI ids for GPU instances.
+   * If the '@aws-cdk/aws-batch:defaultToAL2023' feature flag is set, ECS_AL2023 will be used instead of ECS_AL2.


Note: the '@aws-cdk/aws-batch:defaultToAL2023' feature flag makes the default change backwards compatible for existing customers.

aws-joelherd · 2026-04-07T17:38:24Z

packages/aws-cdk-lib/aws-batch/lib/managed-compute-environment.ts

+      const resolved = image.imageType ?? (
+        FeatureFlags.of(this).isEnabled(cxapi.BATCH_DEFAULT_AL2023)
+          ? EcsMachineImageType.ECS_AL2023
+          : EcsMachineImageType.ECS_AL2
+      );
+      return [EcsMachineImageType.ECS_AL2023, EcsMachineImageType.ECS_AL2023_NVIDIA].includes(resolved);


Note: Expands the validation error for A1 instance types and AL2023 NVIDIA GPU images as well.

aws-joelherd · 2026-04-07T17:42:18Z

packages/aws-cdk-lib/aws-batch/lib/managed-compute-environment.ts

+          userdataType: this.images?.some(image => {
+            const resolved = image.imageType ?? (
+              FeatureFlags.of(this).isEnabled(cxapi.BATCH_DEFAULT_AL2023)
+                ? EksMachineImageType.EKS_AL2023
+                : EksMachineImageType.EKS_AL2
+            );
+            return [EksMachineImageType.EKS_AL2023, EksMachineImageType.EKS_AL2023_NVIDIA].includes(resolved);
+          }) ? 'EKS_NODEADM' : undefined,
        } : undefined,


Note: AL2->AL2023 UserdataType is publicly documented here:

https://docs.aws.amazon.com/batch/latest/userguide/eks-migration-2023.html

https://docs.aws.amazon.com/batch/latest/APIReference/API_LaunchTemplateSpecification.html

aws-joelherd · 2026-04-07T17:46:33Z

packages/aws-cdk-lib/aws-batch/test/managed-compute-environment.test.ts

+    const app = new App({
+      context: { [cxapi.BATCH_DEFAULT_AL2023]: true },
+    });


Note: Unit tests for ECS CEs when feature flag is enabled.

aws-joelherd · 2026-04-07T17:47:49Z

packages/aws-cdk-lib/aws-batch/test/managed-compute-environment.test.ts

+    const app = new App({
+      context: { [cxapi.BATCH_DEFAULT_AL2023]: true },
+    });


Note: Unit tests for EKS CEs when feature flag is enabled.

aws-joelherd · 2026-04-07T17:50:27Z

packages/aws-cdk-lib/aws-batch/test/managed-compute-environment.test.ts

+    });
+  });
+
+  test('sets userdataType to EKS_NODEADM when launch template is used with EKS_AL2023', () => {


Note: Unit tests for EKS CEs and their Userdata Type based on ImageType.

aws-joelherd · 2026-04-07T17:50:54Z

packages/aws-cdk-lib/aws-batch/test/managed-compute-environment.test.ts

+    const app = new App({
+      context: { [cxapi.BATCH_DEFAULT_AL2023]: true },
+    });


Note: Unit tests for EKS CEs and their Userdata Type based on ImageType, with feature flag enabled.

aws-joelherd · 2026-04-07T17:54:54Z

packages/aws-cdk-lib/cx-api/lib/features.ts

+
+  //////////////////////////////////////////////////////////////////////
+  [BATCH_DEFAULT_AL2023]: {
+    type: FlagType.ApiDefault,


Note: This is the default behavior of service API's since January 2026.

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github-actions bot added beginning-contributor [Pilot] contributed between 0-2 PRs to the CDK effort/medium Medium work item – several days of effort feature-request A feature should be added or improved. p2 labels Apr 7, 2026

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aws-joelherd changed the title ~~feat(batch): add AL2023 image types and default to AL2023~~ feat(batch): add AL2023 image types and default to AL2023 (under feature flag) Apr 7, 2026

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feat(batch): add AL2023 image types and default to AL2023 (under feature flag)#37539

feat(batch): add AL2023 image types and default to AL2023 (under feature flag)#37539
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		* - ECS_AL2 compatible AMI ids for non-GPU instances, ECS_AL2_NVIDIA compatible AMI ids for GPU instances.
		* If the '@aws-cdk/aws-batch:defaultToAL2023' feature flag is set, ECS_AL2023 will be used instead of ECS_AL2.

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