lint.yml

name: Lint

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  lint:
    name: Lint code
    runs-on: ubuntu-latest

    env:
      # Configure pip to cache dependencies and do a user install
      PIP_NO_CACHE_DIR: false
      PIP_USER: 1

      # Hide the graphical elements from pipenv's output
      PIPENV_HIDE_EMOJIS: 1
      PIPENV_NOSPIN: 1

      # Make sure pipenv does not try reuse an environment it's running in
      PIPENV_IGNORE_VIRTUALENVS: 1

      # Specify explicit paths for python dependencies
      # so we know which directories to cache
      PYTHONUSERBASE: ${{ github.workspace }}/.cache/py-user-base

    steps:
      - name: Add custom PYTHONUSERBASE to PATH
        run: echo '${{ env.PYTHONUSERBASE }}/bin/' >> $GITHUB_PATH

      - name: Checkout branch
        uses: actions/checkout@v2

      - name: Setup Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.9'

      # This step caches our Python dependencies. To make sure we
      # only restore a cache when the dependencies, the python version,
      # the runner operating system, and the dependency location haven't
      # changed, we create a cache key that is a composite of those states.
      #
      # Only when the context is exactly the same, we will restore the cache.
      - name: Python Dependency Caching
        uses: actions/cache@v2
        id: python_cache
        with:
          path: ${{ env.PYTHONUSERBASE }}
          key: "python-0-${{ runner.os }}-${{ env.PYTHONUSERBASE }}-\
          ${{ steps.python.outputs.python-version }}-\
          ${{ hashFiles('./Pipfile', './Pipfile.lock') }}"

      # Install our dependencies if we did not restore a dependency cache
      - name: Install dependencies
        if: steps.python_cache.outputs.cache-hit != 'true'
        run: |
          pip install pipenv
          pipenv install --dev --deploy --system

      # Run flake8 and have it format the linting errors in the format of
      # the GitHub Workflow command to register error annotations. This
      # means that our flake8 output is automatically added as an error
      # annotation to both the run result and in the "Files" tab of a
      # pull request.
      #
      # Format used:
      # ::error file={filename},line={line},col={col}::{message}
      - name: Run flake8
        run: "flake8 \
        --format='::error file=%(path)s,line=%(row)d,col=%(col)d::\
        [flake8] %(code)s: %(text)s'"