name: Build Docker image

on:
  - push
  - pull_request

permissions:
  contents: read

jobs:
  build:
    runs-on: ubuntu-24.04

    permissions:
      packages: write

    steps:
    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
      with:
        fetch-depth: 0 # fetch all history including tags -- necessary to determine the version from SCM

    - name: Log in to the Container registry
      uses: docker/login-action@5e57cd118135c172c3672efd75eb46360885c0ef
      with:
        registry: ghcr.io
        username: ${{ github.actor }}
        password: ${{ secrets.GITHUB_TOKEN }}

    - name: Build and push Docker image
      id: push
      uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83
      with:
        push: ${{ startsWith(github.ref, 'refs/tags/') }} # only push to ghcr.io on tags
        tags: ghcr.io/${{github.repository}}:latest
        context: . # use the current directory as context, as checked out by actions/checkout -- needed for setuptools_scm
