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python-version

Move every Python service to Python 3.12.

Uses: gha.set_input, python.set_requires_python, runtime.set_version

Start a campaign from it, then point it at your organization:

gh fleet init --from python-version --org your-org

Campaign

load("@fleet//gha.star", "set_input")
load("@fleet//python.star", "set_requires_python")
load("@fleet//runtime.star", "set_version")

def change(repo):
    version = env["PYTHON"]
    set_version(repo, "python", version)
    set_requires_python(repo, ">=" + version)
    # Only plain version pins: leave matrix expressions such as ${{ matrix.py }}
    # alone, and never lower a job that already tests a newer Python.
    set_input(repo, "python-version", version, match = r"^\d", never_lower = True)

# yaml-language-server: $schema=https://raw.githubusercontent.com/rossedman/gh-fleet/main/internal/campaign/campaign.schema.json
apiVersion: fleet.gh/v1
name: python-3-12
description: Move every Python service to Python 3.12

targets:
  orgs: [acme]
  include:
    languages: [Python]

change:
  steps:
    # Updates .python-version, .tool-versions, `requires-python` and the
    # python-version input of actions/setup-python, wherever each is used.
    - name: python version
      starlark: ./change.star
      timeout: 1m
  env:
    PYTHON: "3.12"

pr:
  title: "build: python 3.12"
  body: |
    Moves {{ .Repo.Name }} to Python 3.12: the version files, the
    `requires-python` floor and the version CI installs.

    Opened by the `{{ .Campaign.Name }}` campaign with [gh fleet](https://github.com/rossedman/gh-fleet).
  draft: true
  labels: [fleet]

Test cases

gh fleet test runs the change on each case's before/ files and checks the result against after/. See Testing a campaign.

already-newer

.github/workflows/release.yml

jobs:
  build:
    steps:
      - uses: actions/setup-python@v6
        with:
          python-version: "3.15"
          allow-prereleases: true

pyproject.toml

[project]
name = "black"
requires-python = ">=3.13"

No changes: the campaign leaves this repo alone.

upgrade

.github/workflows/ci.yml

jobs:
  test:
    strategy:
      matrix:
        python: ["3.10", "3.11"]
    steps:
      - uses: actions/setup-python@v5
        with:
          python-version: ${{ matrix.python }}
  lint:
    steps:
      - uses: actions/setup-python@v5
        with:
          python-version: "3.10"

.python-version

3.11

pyproject.toml

[project]
name = "api"
requires-python = ">=3.10"

.github/workflows/ci.yml

jobs:
  test:
    strategy:
      matrix:
        python: ["3.10", "3.11"]
    steps:
      - uses: actions/setup-python@v5
        with:
          python-version: ${{ matrix.python }}
  lint:
    steps:
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"

.python-version

3.12

pyproject.toml

[project]
name = "api"
requires-python = ">=3.12"

Source on GitHub