This is a good starting point for getting Python, Django, Postgres running as a service, pytest, black, and pip caching rolling with GitHub Actions.

python-django-postgres-ci.yml

name: CI

on: [push]

jobs:

  test:
    runs-on: ubuntu-latest

    services:
      postgres:
        image: postgres:11
        env:
          POSTGRES_USER: postgres
          POSTGRES_PASSWORD: postgres
          POSTGRES_DB: postgres
        ports: ['5432:5432']
        options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5

    steps:
      - uses: actions/checkout@v1
        with:
          fetch-depth: 1

      - name: Set up Python 3.7
        uses: actions/setup-python@v1
        with:
          python-version: 3.7

      - uses: actions/cache@v1
        with:
          path: ~/.cache/pip
          key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
          restore-keys: |
            ${{ runner.os }}-pip-

      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          python -m pip install -r requirements.txt
        if: steps.cache.outputs.cache-hit != 'true'

      - name: Test with black
        run: |
          python -m black --check .

      - name: Test with pytest
        env:
          DATABASE_URL: 'postgres://postgres:postgres@localhost:${{ job.services.postgres.ports[5432] }}/postgres'
        run: |
          python -m pytest

z-docker-publish.yml

name: docker-publish

on:
  push:
    branches:
      - master

jobs:

  docker:
    name: Build and Publish Docker image
    runs-on: ubuntu-latest

    steps:
      - name: Git - Get Sources
        uses: actions/checkout@v1
        with:
          fetch-depth: 1

      - name: Docker - Build
        run: |
          docker build . --file .docker/Dockerfile --tag changeme-web

      - name: Docker - Login
        run: |
          echo ${{ secrets.GITHUB_TOKEN }} | docker login docker.pkg.github.com --username ${{ github.actor }} --password-stdin

      - name: Docker - Tag
        run: |
          docker tag changeme-web docker.pkg.github.com/${{ github.repository }}/changeme-web:latest

      - name: Docker - Push
        run: |
          docker push docker.pkg.github.com/${{ github.repository }}/changeme-web:latest

I believe that 5432 may not always be available on the host. https://github.com/actions/example-services/blob/master/.github/workflows/postgres-service.yml shows how to bind it to a random TCP port on local host and then pass that as an env var in later steps. Using services in these jobs is awesome though!

@sburns thanks for the tip. I updated the config and can confirm that it just worked.

Also ymmv on this one, but we install pyscopg2 from source so I needed to apt-get install -y libpq-dev for Postgres headers to be nearby.

For people looking for Pipenv support, here is what I ended up with after a lots of fiddling, the import bit is setting up the WORKON and PIPENV_CACHE_DIR to the same directory as the whole directory will be cached.

      - name: Install pipenv
        uses: dschep/install-pipenv-action@v1

      - name: Cache Pipenv virtualenv
        uses: actions/cache@v1
        id: pipenv-cache
        with:
          path: ~/.pipenv
          key: ${{ runner.os }}-pipenv-v2-${{ hashFiles('**/Pipfile.lock') }}
          restore-keys: |
            ${{ runner.os }}-pipenv-v2-

      - name: Install Dependencies
        env:
          PIPENV_NOSPIN: 'true'
          WORKON_HOME: ~/.pipenv/virtualenvs
          PIPENV_CACHE_DIR: ~/.pipenv/pipcache
        run: pipenv install --dev
        if: steps.pipenv-cache.outputs.cache-hit != 'true'

      - name: Test with pytest
        env:
          PIPENV_NOSPIN: 'true'
          WORKON_HOME: ~/.pipenv/virtualenvs
          REDIS_HOST: localhost
          REDIS_PORT: ${{ job.services.redis.ports[6379] }}
          DATABASE_URL: 'postgres://postgres:postgres@localhost:${{ job.services.postgres.ports[5432] }}/test_db'
          DJANGO_SECRET_KEY: 'KEY'
          DJANGO_SETTINGS_MODULE: CONFIG'
          PYTHONPATH: '.'
          DJANGO_DEBUG: 'False'
        run: |
          pipenv run python manage.py migrate --noinput
          pipenv run pytest 

@arnaudlimbourg that's great!

It was indeed a great starting point.

Though I had some problems with the URL string overwriting Heroku configuration. I've solved that problem by forwarding database related settings as environment variables (same as you do with database URL) and using the values in the DATABASES setting:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.environ.get('PG_NAME', 'pgdb'),
        'USER': os.environ.get('PG_USER', 'pguser'),
        'PASSWORD': os.environ.get('PG_PWD', 'pgpwd'),
        'HOST': os.environ.get('PG_HOST', 'localhost'),
        'PORT': os.environ.get('PG_PORT', '5432'),
    }
}

thank you!