How to Cache pip Downloads in GitHub Actions

Cache the directory from pip cache dir keyed on requirements.txt so pip reuses downloaded and built wheels.

pip keeps a download and wheel cache so it does not refetch or rebuild packages. Cache that directory (resolved with pip cache dir) keyed on your requirements files, not the installed site-packages.

Steps

• Resolve the cache path with pip cache dir into a step output.
• Cache that path keyed on hashFiles('**/requirements*.txt').
• Run pip install -r requirements.txt.

Workflow

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
  - id: pip
    run: echo "dir=$(pip cache dir)" >> "$GITHUB_OUTPUT"
  - uses: actions/cache@v4
    with:
      path: ${{ steps.pip.outputs.dir }}
      key: pip-${{ runner.os }}-${{ hashFiles('**/requirements*.txt') }}
      restore-keys: |
        pip-${{ runner.os }}-
  - run: pip install -r requirements.txt

Gotchas

• actions/setup-python has a built-in cache: pip input that caches this automatically when you point it at your requirements file.
• Cache the download cache, not the virtualenv; a stale env can mask dependency changes.

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