name: ci
on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: environment
        run: |
          echo "arch: $(uname -m)"
          echo "runner works"

      - name: run tests
        run: |
          python3 -c "assert 2 + 2 == 4; print('test passed')"

      - name: build a docker image
        run: |
          cat > Dockerfile <<'DOCKER'
          FROM alpine:latest
          RUN echo "built on $(uname -m)" > /where
          CMD cat /where
          DOCKER
          docker build -t ci-demo:${GITHUB_SHA::7} .
          docker run --rm ci-demo:${GITHUB_SHA::7}