PYTHON-6077 Officially support Python 3.15 by blink1073 · Pull Request #3042 · mongodb/mongo-python-driver

blink1073 · 2026-09-05T00:00:31Z

PYTHON-6077

Changes in this PR

Added Python 3.15 (standard and free-threaded) to the Evergreen test matrix and wheel builds.
Fixed enterprise-auth keytab decoding for Python 3.15's stricter base64.
Fixed async_socket_sendall for compatibility with Python 3.15. This is the trickiest change.
Added the Python 3.15 classifier and changelog entry.
Most of the lines of code in the diff are from the regenerated tasks spanning the new python verisons.

Test Plan

Ran an Evergreen patch across all the new Python 3.15 builds.
Since 3.15 is now the max CPython ( MIN_MAX_PYTHON[-1]), it runs in 80 of the PR tasks.

Checklist

Checklist for Author

Did you update the changelog (if necessary)?
Is there test coverage? Added Evergreen CI coverage for the new versions.
Is any followup work tracked in a JIRA ticket? If so, add link(s). N/A

Checklist for Reviewer

Does the title of the PR reference a JIRA Ticket?
Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
Is all relevant documentation (README or docstring) updated?

…7-officially-support-py315 # Conflicts: # .evergreen/generated_configs/tasks.yml

This reverts commit 78b8a2e.

codecov · 2026-09-05T01:47:57Z

Codecov Report

❌ Patch coverage is 75.00000% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pymongo/network_layer.py	75.00%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!

…version

blink1073 · 2026-09-08T13:12:51Z

            write_env("KRB5_CONFIG", krb_conf)
            LOGGER.info("Writing keytab")
-            keytab = base64.b64decode(config["KEYTAB_BASE64"])
+            keytab_b64 = config["KEYTAB_BASE64"]


This change was needed for Python 3.15 support

Copilot

🟡 Changes recommended

The fallback selects a 64-bit interpreter for Win32 coverage and performs avoidable rate-limited API requests.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds official Python 3.15 and free-threaded 3.15 support across packaging and CI.

Changes:

Adds Python 3.15 metadata, changelog, tests, and wheels.
Standardizes CI interpreter selection through UV_PYTHON.
Adds a python-build-standalone fallback and stricter keytab decoding.

File summaries

File	Description
`pyproject.toml`	Adds the Python 3.15 classifier.
`doc/changelog.rst`	Documents Python 3.15 support.
`.github/workflows/dist.yml`	Builds and verifies 3.15 wheels.
`.evergreen/scripts/setup-uv-python.sh`	Resolves toolchain interpreters.
`.evergreen/scripts/setup-dev-env.sh`	Installs or fetches missing interpreters.
`.evergreen/scripts/setup_tests.py`	Corrects keytab Base64 padding.
`.evergreen/scripts/generate_config.py`	Generates `UV_PYTHON`-based tasks.
`.evergreen/scripts/generate_config_utils.py`	Defines 3.15 versions and helpers.
`.evergreen/scripts/fetch-python.sh`	Fetches standalone Python builds.
`.evergreen/generated_configs/variants.yml`	Adds 3.15 compression variants.
`.evergreen/generated_configs/tasks.yml`	Adds and migrates generated tasks.
`.evergreen/generated_configs/functions.yml`	Propagates `UV_PYTHON`.

Review details

Suppressed comments (1)

.evergreen/scripts/fetch-python.sh:35

This unauthenticated GitHub API request runs before the existing-install check at line 53, so every repeated setup still consumes a request even after the large interpreter has been cached. Python 3.15 tasks source this setup more than once, making shared CI egress susceptible to GitHub's unauthenticated rate limit and causing otherwise cached jobs to fail. Resolve the cache path and return it before querying the release API, or cache the release metadata separately.

release="$(curl -fsSL --retry 3 https://api.github.com/repos/astral-sh/python-build-standalone/releases/latest)"

Files reviewed: 11/12 changed files
Comments generated: 1
Review effort level: Balanced

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Copilot

🟡 Changes recommended

The new python-build-standalone fallback currently sets UV_PYTHON to a directory (not an interpreter path), which is inconsistent with how UV_PYTHON is handled elsewhere and can break uv run interpreter selection.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

doc/changelog.rst:4

The changelog header uses an invalid date placeholder ("2026/XX/XX"), which can be confusing and may break tooling that expects a real date. Consider using an explicit "Unreleased" marker until the release date is known.

Files reviewed: 11/12 changed files
Comments generated: 1
Review effort level: Lite

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

…7-officially-support-py315 # Conflicts: # doc/changelog.rst

…support-py315' into worktree-PYTHON-6077-officially-support-py315

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Copilot

🟡 Changes recommended

Timeout cleanup can race with an active socket worker, and FIPS warning handling can incorrectly report FIPS as disabled.

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Review details

Files reviewed: 19/19 changed files
Comments generated: 2
Review effort level: Balanced

…fork warning suppression

Copilot

🟡 Changes recommended

Worker exceptions can mask cancellation, and the wheel check can pass without a standard CPython 3.15 wheel.

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Review details

Files reviewed: 19/19 changed files
Comments generated: 2
Review effort level: Balanced

… timeout on worker failure

Copilot

🟡 Changes recommended

Repeated cancellation can still let the socket worker outlive its caller, and the TLS compatibility path lacks direct regression coverage.

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Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

pymongo/network_layer.py:84

The Python 3.15 compatibility fix itself is not covered: the added tests call the generic helper with len/sleep functions, but none invokes async_socket_sendall with a TLS socket. Please add a regression test that exercises this branch and verifies the peer-reset translation (and ideally timeout translation), so the behavior described by this PR cannot regress while the helper tests still pass.

Files reviewed: 19/19 changed files
Comments generated: 1
Review effort level: Balanced

Copilot

🔵 Needs a closer look

The asynchronous SSL timeout behavior and extensive generated CI matrix warrant final human validation.

Review details

Files reviewed: 19/19 changed files
Comments generated: 0 new
Review effort level: Balanced

codeowners-service-app · 2026-09-18T11:41:27Z

Assigned sleepyStick for team dbx-python because aclark4life is out of office.

sleepyStick

took me a minute to understand what was happening but i think i get it now lol great work!

blink1073 added 6 commits September 4, 2026 11:11

PYTHON-6077 Officially support Python 3.15

11f1822

PYTHON-6077 Always use UV_PYTHON and prefer toolchain pythons

82afc1a

Merge remote-tracking branch 'upstream/main' into worktree-PYTHON-607…

4098a2e

…7-officially-support-py315 # Conflicts: # .evergreen/generated_configs/tasks.yml

PYTHON-6077 Drop the python-build-standalone fallback for 3.15

78b8a2e

Revert "PYTHON-6077 Drop the python-build-standalone fallback for 3.15"

620507f

This reverts commit 78b8a2e.

PYTHON-6077 Handle remaining 3.15 CI failures

f6be3d0

blink1073 added 2 commits September 8, 2026 07:54

PYTHON-6077 Generalize python-build-standalone fetch for any missing …

4841077

…version

PYTHON-6077 Clarify python download conditions in setup-dev-env

2a2c0c6

blink1073 commented Sep 8, 2026

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Comment thread .evergreen/scripts/fetch-python.sh Outdated

Handle x86_64 architecture for Windows and others

a70b3a5

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Comment thread .evergreen/scripts/setup-dev-env.sh Outdated

blink1073 and others added 13 commits September 8, 2026 08:36

Refactor Python interpreter setup in setup-dev-env.sh

5a34041

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PYTHON-6077 Fix missing fi in setup-dev-env.sh

f3acdf1

PYTHON-6077 Accept unpadded/whitespace-padded keytab on 3.15

133c3bb

PYTHON-6077 Strip internal whitespace from keytab base64

1f56904

PYTHON-6077 Decode keytab with lenient padding on 3.15

473ed18

Merge remote-tracking branch 'upstream/main' into worktree-PYTHON-607…

6501c2f

…7-officially-support-py315 # Conflicts: # doc/changelog.rst

PYTHON-6077 Make test_list_collections robust to empty test db

778de06

PYTHON-6077 Clone drivers-tools module regardless of env.sh

27bcd1e

PYTHON-6077 Use PATH-based Python resolution with bare UV_PYTHON

269e79b

PYTHON-6077 Scope UV_PYTHON_PREFERENCE=system to non-Windows

95e0e90

PYTHON-6077 Use path-based UV_PYTHON on Windows

ea36a45

PYTHON-6077 Skip fetch fallback on re-entry by marking Python resolved

461b5b1

PYTHON-6077 Add KMS-DEBUG ssl diagnostics (temporary)

81ca2a4

blink1073 added 3 commits September 17, 2026 09:28

Merge branch 'main' into worktree-PYTHON-6077-officially-support-py315

e7f6c82

Merge remote-tracking branch 'origin/worktree-PYTHON-6077-officially-…

ddcdebb

…support-py315' into worktree-PYTHON-6077-officially-support-py315

PYTHON-6077 Wait for the KMS send worker on cancellation too

09b4da6

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Comment thread pymongo/network_layer.py Outdated

Comment thread test/asynchronous/__init__.py Outdated

PYTHON-6077 Wait for the KMS send worker unconditionally and fix the …

bf387a1

…fork warning suppression

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Comment thread .github/workflows/dist.yml Outdated

Comment thread pymongo/network_layer.py Outdated

PYTHON-6077 Match the standard wheel exactly and surface the original…

3aee647

… timeout on worker failure

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Comment thread pymongo/network_layer.py Outdated

PYTHON-6077 Shield the KMS send cleanup from further cancellations

e136129

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PYTHON-6077 Trim the socket-call cleanup comment

78b35aa

blink1073 marked this pull request as ready for review September 18, 2026 11:41

blink1073 requested a review from a team as a code owner September 18, 2026 11:41

blink1073 requested a review from aclark4life September 18, 2026 11:41

codeowners-service-app Bot requested a review from sleepyStick September 18, 2026 11:41

sleepyStick approved these changes Sep 18, 2026

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blink1073 merged commit b566879 into mongodb:main Sep 18, 2026
90 of 94 checks passed

blink1073 deleted the worktree-PYTHON-6077-officially-support-py315 branch September 18, 2026 22:06

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