create_cache.yml

name: "Create GHA cache"

# GitHub puts the following restrictions on cache sharing. PRs can access
#
# - caches that were created by the PR / earlier runs of the PR
# - caches that were created on the target branch
#
# To get effective cache sharing between PRs, we create caches on the `develop`
# branch (which is where almost all PRs merge into).

on:
  push:
    branches: [develop]

# Cancel running jobs if there's a newer push
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  # GitHub Actions cache of the pre-commit environment
  pre-commit:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v6

      - name: Setup Python 3.12
        uses: actions/setup-python@v6
        with:
          python-version: '3.12'

      - uses: actions/cache@v5
        id: cache
        with:
          path: ~/.cache/pre-commit
          key: pre-commit_${{ env.pythonLocation }}_${{ hashFiles('.pre-commit-config.yaml') }}
          lookup-only: true  # don't actually download the cache

      - name: Populate pre-commit environment (if not cached)
        if: steps.cache.outputs.cache-hit != 'true'
        run: |
          pip install pre-commit
          pre-commit install --install-hooks