[leandrodamascena]

Issue number: Refs #8543

Summary

Changes

Prepare Python 3.15 across CI, E2E infrastructure, layer builds, canaries, SAR, partition workflows and SSM parameters. Keep Python 3.10–3.14 in the test matrices and remove the obsolete Python 3.9 runtime from the E2E helper.

Refresh the locked versions of cffi, regex and rpds-py for 3.15 compatibility, retaining the older rpds-py release on Python 3.10. Install the protobuf compiler only in the 3.15 test jobs while Valkey GLIDE needs a source build. Fix shell lint findings in the touched workflows; existing SSM arguments and partition outputs were checked against develop.

CDK uses Runtime("python3.15", RuntimeFamily.PYTHON, supports_inline_code=True) until the named constant is available. The layer construct's default runtime remains unchanged.

Make the Decimal/Enum test fixture preserve its identity during deepcopy with both Decimal implementations. This fixes the four CI failures under _pydecimal while retaining the existing hash and JMESPath assertions.

User experience

This is a draft to prepare support. The installation docs link to the tracking issue without advertising unpublished layers or SAR applications.

Validation

• Python 3.10.21 and 3.15.0 final on ARM64: 3,531 tests and 10 performance tests passed on each.
• Reproduced the four CI failures by disabling _decimal. After the fixture fix, all 33 serialization cases passed with native and pure-Python Decimal on both 3.10 and 3.15; the full 3.15 suite passed again with _decimal disabled: 3,531 tests and 10 performance tests.
• All 13 Nox sessions passed on 3.15, with the Datadog compatibility caveat below.
• mypy, ty, Ruff, security and complexity baselines, and all applicable pre-commit hooks passed.
• All 20 layer constructor tests passed with Docker assets stubbed. Layer and canary templates synthesized for 3.10–3.15 and both architectures; the E2E helper rejects 3.9.
• Binary dependency downloads for [all,redis,datamasking] passed for Python 3.15 on x86_64 and ARM64.
• Full docs lint still reports the existing MD053 warning in the unchanged docs/changelog.md; lint passed for the edited page.

Before merge

• Validate Lambda runtime availability, E2E deployments and real layer builds on both architectures. The public Lambda 3.15 and SAM build images were unavailable during validation. The CDK job passed 18 tests and failed only the two 3.15 image builds.
• Resolve Datadog support: source installation and tests passed, but uv pip check rejects datadog-lambda 8.128.0 and ddtrace 4.15.6 because both declare Python <3.15.
• Resolve the new Streaming finalization warning. test_s3_csv_stream fails on 3.15 with -W error::pytest.PytestUnraisableExceptionWarning because _S3SeekableIO.flush() raises while TextIOWrapper is finalized. The same check passes on 3.10.
• Confirm runtime availability in the target regions and partitions before enabling deployment. Layer/SAR publication and the final supported-runtime docs remain tracked in Maintenance: Support for Python 3.15 #8543.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.91%. Comparing base (073b5ba) to head (95cff91).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8544   +/-   ##
========================================
  Coverage    96.91%   96.91%           
========================================
  Files          317      317           
  Lines        15959    15959           
  Branches      1411     1411           
========================================
  Hits         15467    15467           
  Misses         349      349           
  Partials       143      143           

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Suraj1347]

Hi, I noticed the test_s3_csv_stream issue mentioned in the PR on Python 3.15. I was thinking of looking into it and seeing if I can fix it. Would you be okay with me taking a look and putting up a separate PR if I find a solution?

[leandrodamascena]

Hi @Suraj1347, thanks for offering. I'd rather keep this one with me, though. Python 3.15 support has to be coordinated with the Lambda team around the runtime release, so the fix for test_s3_csv_stream will land together with the rest of this PR when that happens.

If you want something to pick up, two places: anything under the good first issue label, and the Idempotency list in #8603. The ones in the discussion don't have issues yet, so if you pick one, say which one there and I'll open the issue and assign it to you.

Your two Parameters PRs, #8622 and #8623, are in the 3.39.0 queue and I'll get to them soon.

[Suraj1347]

Thanks for the update! I'll check out the Idempotency discussion and the good first issues to see what I can pick up. Glad to hear that PRs #8622 and #8623 are in the 3.39.0 queue. Thanks for taking a look at them!