[rgoltz]

Issue # (if applicable)

Closes #37510.

Reason for this change

FargateService currently throws EphemeralStorageGibFeatureRequires when ephemeralStorageGiB is set and the Fargate platform version is < 1.4.0.

This validation is correct for Linux tasks, but incorrect for Windows tasks: according to the ECS documentation, Windows Fargate supports task ephemeral storage starting with platform version 1.0.0.

Description of changes

• Added a public getter for TaskDefinition.runtimePlatform so FargateService can determine the task operating system family.
• Updated FargateService validation to only require platform version >= 1.4.0 for ephemeralStorageGiB on non-Windows (Linux) tasks.
• Updated the ephemeralStorageGiB documentation to reflect the different minimum platform versions for Linux vs. Windows tasks.
• Added a unit test verifying that setting ephemeralStorageGiB on a Windows Fargate task definition with platform version 1.0.0 does not fail during synth.

Alternatives considered:

• Removing the validation entirely (rejected: Linux requires 1.4.0+).
• Introducing a separate public API just for the OS family (rejected: runtimePlatform already models the required information).

Describe any new or updated permissions being added

None.

Description of how you validated changes

• Added a unit test in packages/aws-cdk-lib/aws-ecs/test/fargate/fargate-service.test.ts that synthesizes a Windows Fargate service using platformVersion: VERSION1_0 and ephemeralStorageGiB.
• Existing unit test coverage for the Linux restriction (platform version < 1.4.0) remains unchanged.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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

[aws-cdk-automation]

(This review is outdated)

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[rgoltz]

Added an integ snapshot test to provide coverage for this behavior (as best as possible) and to guard against regressions.

• CDK does not fail at construct validation / synth when ephemeralStorageGiB is set for a Windows Fargate task while using platformVersion: 1.0.0.
• The synthesized template includes the expected CFN properties:
  • AWS::ECS::TaskDefinition.EphemeralStorage.SizeInGiB
  • AWS::ECS::TaskDefinition.RuntimePlatform (Windows/X86_64)
  • AWS::ECS::Service.PlatformVersion = 1.0.0 (captured in the snapshot)

It does not attempt to run a Windows task or validate container startup/image pull on Fargate: Start a Windows Image takes many time and could might result in a flakiness/latency to CI. Hence, I uses desiredCount: 0 to keep integ runs stable while still exercising synth + snapshot coverage. I (the integ-runner) successfully created the stack + service in my AWS account.

[kumvprat]

Thanks for this fix

I left three small, non-blocking suggestions inline (error-message clarity for the tokenized-OS edge case, a note on the public-getter API surface, and a positive template assertion in the unit test).

[maintainer-for-aws]

Automated review

A maintainer will still review this — treat the notes below as a starting point.

This PR fixes over-restrictive client-side validation in aws-ecs so that Windows Fargate tasks with ephemeralStorageGiB are no longer rejected on platform version 1.0.0, aligning CDK with documented ECS behavior (Linux requires 1.4.0+, Windows requires 1.0.0+). The change narrows the FargateService guard to skip the check for Windows and for unresolved (token) OS families, exposes a new public read-back getter runtimePlatform on TaskDefinition (renaming the backing field to _runtimePlatform), and updates the related doc comments. It is accompanied by two new unit tests (the Windows happy path and the tokenized-OS defer path), a preserved negative test for Linux < 1.4.0, and a new integration test with a synthesized snapshot. The narrowed validation still rejects Linux tasks below 1.4.0, the field rename touches no public surface, and the new getter is a backward-compatible additive change returning an existing public type. No issues found on this change.

🔴 0 blocking · 🟡 0 recommended · ⚪ 0 optional

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[kumvprat]

LGTM!! Thanks for the effort on this PR

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-09-09 17:33 UTC · Rule: default-squash · triggered by rule automatic merge
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-09-09 17:38 UTC · at 855dfeb67c8cba8cd5cc58f6e72e9de36ff92cf3 · squash

This pull request spent 5 minutes in the queue, including 4 minutes 47 seconds running CI.

Required conditions to merge

• github-review-approved [🛡 GitHub branch protection]
  • fix(ecs): allow ephemeralStorageGiB for Windows Fargate platform version 1.0.0 #37589
• any of [🛡 GitHub branch protection]:
  • check-success = validate-pr
  • check-neutral = validate-pr
  • check-skipped = validate-pr
• any of [🛡 GitHub branch protection]:
  • check-success = build
  • check-neutral = build
  • check-skipped = build

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

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