action.yml

name: Setup Python and Poetry
description: Setup Python and Poetry. Cribbed from snok/install-poetry.
inputs:
  working-directory:
    description: Directory where the action will execute its commands. Defaults to repository root.
    required: false
    default: "./"
  python-version:
    description: Python version to pass to actions/setup-python@v4.
    required: false
    default: "3.x"
  poetry-version:
    description: Poetry version to install via pip.
    required: false
    default: "2.1.1"
  extras:
    description: >
      If present, a space-separated list of extras to pass to
      `poetry install --extra ...`. Either way, dev-dependencies
      will be installed.
    # If https://github.com/python-poetry/poetry/issues/3413 get solved, I think
    # we should make this action install all extras by default.
    required: false
    default: ""
  groups:
    description: >
      If present, a space-separated list of dependency groups to pass to
      `poetry install --with ...`.
    required: false
    default: ""
  install-project:
    description: >
      Set to "false" to disable installing of the project, instead only install
      deps.
    required: false
    default: "true"
runs:
  using: composite
  steps:
    # We want to include the OS version in the cache key. We do this by reading
    # `/etc/os-release` and picking some suitable values.
    - name: Get OS version
      id: get-os-version
      run: |
        source /etc/os-release
        echo "cache_os_key=$ID-$VERSION_ID" >> "$GITHUB_OUTPUT"
      shell: bash

    - name: Setup Python
      id: setup-python
      uses: actions/setup-python@v4
      with:
        python-version: ${{ inputs.python-version }}

    - name: Check for poetry lock
      run: "test -f poetry.lock || (echo No lock file! && false)"
      shell: bash
      working-directory: ${{ inputs.working-directory }}

    # Install poetry. It takes ~10seconds for a clean pip install, most of which is
    # the installation rather than the downloading. So instead, we cache the user-base
    # directory (~/.local). For this to be safe:
    # - we must not write to `.local` as part of the CI
    # - we must not install anything with the system `pip` other than poetry.
    # Based on the writeup at:
    # https://github.com/snok/install-poetry/blob/main/README.md#caching-the-poetry-installation
    - name: Locate user site
      id: site-user-base
      run: echo "dir=$(python -m site --user-base)" >> "$GITHUB_OUTPUT"
      shell: bash

    - name: Restore/cache poetry installation
      id: poetry-install-cache
      uses: actions/cache@v3
      with:
        path: ${{ steps.site-user-base.outputs.dir }}
        key: poetry-install-cache-${{ steps.get-os-version.outputs.cache_os_key }}-${{ steps.setup-python.outputs.python-version }}-${{ inputs.poetry-version }}

    - name: Install poetry from scratch
      if: "${{ steps.poetry-install-cache.outputs.cache-hit != 'true' }}"
      run: python -m pip install --user poetry==${{ inputs.poetry-version }}
      shell: bash

    # Poetry manages a virtualenv for us. We're going to cache that too.
    # Again, we're following snok/install-poetry's README.
    - name: Locate poetry venv
      id: poetry-venvs
      run: |
        echo "dir=$(python -m poetry env info -p || echo $(pwd)/.venv)" >> "$GITHUB_OUTPUT"
      shell: bash
      working-directory: ${{ inputs.working-directory }}

    - name: Restore/cache poetry venv
      id: poetry-venv-cache
      uses: actions/cache@v3
      with:
        path: ${{ steps.poetry-venvs.outputs.dir }}
        key: poetry-venv-${{ runner.os }}-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('poetry.lock') }}-${{ inputs.extras }}

    - name: Check that the poetry lockfile is up to date
      run: poetry check --lock
      shell: bash
      working-directory: ${{ inputs.working-directory }}

    - name: Install project
      run: poetry install -vv --no-interaction ${ARG_EXTRAS:+--extras="$ARG_EXTRAS"} ${ARG_GROUPS:+--with="$ARG_GROUPS"} ${ARG_INSTALL:+"$ARG_INSTALL"}
      shell: bash
      env:
        # we pass these as env vars to make sure these values don't get expanded as extra arguments or shell directives
        ARG_EXTRAS: "${{ inputs.extras }}"
        ARG_GROUPS: "${{ inputs.groups }}"
        ARG_INSTALL: "${{ inputs.install-project != 'true' && '--no-root' || '' }}"
      working-directory: ${{ inputs.working-directory }}

    # For debugging---let's just check what we're working with.
    - name: Dump virtual environment
      run: |
        poetry env info
        poetry run pip list
      shell: bash
      working-directory: ${{ inputs.working-directory }}