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Python 3.9 to 3.13 Upgrade Planner: Removed Stdlib Modules Sweep, Dependency Wheel Check, Stepwise Version Hops, CI Matrix, and a Rollback Plan
Plan a Python 3.9 to 3.13 upgrade for a service or library: find imports of stdlib modules removed in 3.12 and 3.13, check that pinned dependencies ship wheels for the new version, choose stepwise hops, set up a CI matrix, and keep a rollback path.
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Prompt
Act as a Python platform engineer who moves services and libraries off end of life Python 3.9 to 3.13, sweeps code for removed standard library modules, checks dependency wheels, and runs the upgrade in stepwise hops behind a CI matrix. Inputs: - Project type (web service, CLI, data pipeline, published library) and deployment target (Docker base image, Lambda runtime, VM): [ProjectAndRuntime] - Pinned dependencies with versions from requirements.txt, poetry.lock, or uv.lock: [DependencyPins] - Output of a grep for imports and calls you are unsure about (for example imp, distutils, asyncore, cgi, telnetlib, pipes, crypt, imghdr, lib2to3): [ImportGrep] - Native extensions or C dependencies you build yourself: [NativeDeps] - CI system and current test matrix: [CiMatrix] - Release constraints (freeze windows, how many deploys per week): [ReleaseConstraints] - Output format: [Format] Generate: 1. A removed module sweep from ImportGrep: each hit, the version that removed it (distutils, imp, asynchat, asyncore in 3.12; cgi, cgitb, crypt, telnetlib, nntplib, pipes, audioop, imghdr, sndhdr, uu, xdrlib, lib2to3 and the rest of the PEP 594 set in 3.13), and the replacement. 2. A dependency wheel table from DependencyPins: package, current pin, first version with 3.13 wheels or pure Python support as [confirm on PyPI], and upgrade risk. 3. A native extension note for NativeDeps: rebuild needs, and whether free threaded builds matter (usually not for this upgrade). 4. A hop plan: 3.9 to 3.11, then 3.11 to 3.13, or a direct jump, with the reason based on ProjectAndRuntime and ReleaseConstraints. 5. A CI matrix change for CiMatrix that runs the old and new versions side by side, with warnings turned into errors for DeprecationWarning on your own code. 6. A runtime switch checklist: base image or runtime tag, lockfile regeneration, and smoke tests. 7. A rollback plan that keeps the previous image tag deployable for one release cycle. 8. A short risk register with the three most likely breakages. Constraints: - Do not invent package versions or release dates; mark them [confirm on PyPI] or [confirm in release notes]. - Prefer the replacement the standard library docs name (for example importlib for imp, setuptools or packaging for distutils). - Plain engineer tone. No em dashes.
Instructions
Replace every [bracket] with your details before running. Works on ChatGPT, Claude, and Gemini.
Generated Output
This image was generated using the prompt above.
Examples
Example Input
ProjectAndRuntime: Flask web service in Docker, base image python:3.9-slim, deployed to ECS DependencyPins: Flask==2.0.3, gunicorn==20.1.0, psycopg2-binary==2.9.3, pandas==1.3.5, numpy==1.21.6, celery==5.2.7, requests==2.27.1 ImportGrep: app/utils/legacy.py imports imp for imp.reload; scripts/build_ext.py uses distutils.core.setup; app/uploads.py imports imghdr to sniff image type; tests use asynctest NativeDeps: none built in house; psycopg2-binary and numpy wheels from PyPI CiMatrix: GitHub Actions, single job on 3.9 ReleaseConstraints: weekly deploy on Tuesdays; freeze from Dec 15 to Jan 5 Format: sweep, wheel table, native note, hop plan, CI change, switch checklist, rollback, risk register
Example Output
1) REMOVED MODULE SWEEP - app/utils/legacy.py: imp (removed in 3.12). Replace imp.reload with importlib.reload. - scripts/build_ext.py: distutils (removed in 3.12). Move to setuptools.setup or delete the script if it is unused. - app/uploads.py: imghdr (removed in 3.13, PEP 594). Use Pillow's Image.open with verify or check magic bytes directly (PNG 89 50 4E 47, JPEG FF D8 FF). - tests: asynctest is unmaintained and breaks on newer Python. Replace it with unittest.IsolatedAsyncioTestCase and AsyncMock. 2) DEPENDENCY WHEEL TABLE | Package | Pin | Target for 3.13 | Risk | | Flask | 2.0.3 | 3.x [confirm on PyPI] | Medium: Werkzeug 3 changes | | gunicorn | 20.1.0 | 23.x [confirm on PyPI] | Low | | psycopg2-binary | 2.9.3 | 2.9.10 or later with cp313 wheels [confirm on PyPI] | Low | | pandas | 1.3.5 | 2.2.3 or later [confirm on PyPI] | High: 2.x API changes | | numpy | 1.21.6 | 2.1 or later [confirm on PyPI] | High: numpy 2 ABI, follows pandas | | celery | 5.2.7 | 5.4 or later [confirm on PyPI] | Medium | | requests | 2.27.1 | 2.32.x [confirm on PyPI] | Low | 3) NATIVE EXTENSIONS None built in house. Rely on cp313 wheels for psycopg2-binary and numpy. Free threaded builds are not needed for this service. 4) HOP PLAN Two hops. Hop A: 3.9 to 3.11 with Flask 3, gunicorn, requests, celery, and the imp and distutils fixes. Hop B: 3.11 to 3.13 with pandas 2 and numpy 2 plus the imghdr fix. This splits the high risk data stack into its own release and fits weekly Tuesday deploys before the Dec 15 freeze. 5) CI MATRIX strategy.matrix.python-version: ["3.9", "3.11"] during hop A, then ["3.11", "3.13"] during hop B. Run pytest with -W error::DeprecationWarning:app so your own deprecated calls fail fast while third party warnings still print. 6) SWITCH CHECKLIST [ ] Change base image to python:3.11-slim, then python:3.13-slim [ ] Regenerate the lockfile inside the new image [ ] Smoke test: /healthz, one DB write, one Celery task, one image upload [ ] Watch error rates for 24 hours 7) ROLLBACK Keep the last python:3.9 image tag in ECR and the old task definition revision. Rollback is a task definition revert. Keep it for one full release cycle after each hop. 8) RISK REGISTER - pandas 2 removes deprecated APIs used in reports - Werkzeug 3 changes in Flask 3 break a helper import - Image sniffing behaves differently after replacing imghdr