packages.yml

name: Release to Github Packages. # https://ghcr.io
on: # https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#on
  workflow_dispatch:
  push:
    tags: # This builds for all branches with semantically versioned tags (v0.12.3).
      - v* # https://semver.org will fail, if there are any other tags

  #release: # Builds only releases. Includes draft and pre-releases.
    #types: [created]

  #pull_request: # Run 'tests' for any PRs. Default is to not run for first-time contributors: see /settings/actions

env:
  TAG_LATEST: true # Encourage users to use a major version (foobar:1) instead of :latest.
  # By semantic versioning standards, major changes are changes 'backwards incompatible'. Major upgrades are often rare and prehaps, need attention from the user.
jobs:
  # Push image to GitHub Packages.
  push:
    runs-on: ubuntu-latest
    permissions:
      packages: write
      contents: read

    steps:
      - uses: actions/checkout@v2

      - name: Build image
        run: docker build . --file Dockerfile --tag ${{ github.event.repository.name }} --label "runnumber=${GITHUB_RUN_ID}"

      - name: Authenticate with ghcr.io
        run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin

      - name: Push image
        run: |
          # Destiination, trsnform to lowercase
          IMAGE_ID=$(echo ghcr.io/${{ github.repository }} | tr '[A-Z]' '[a-z]')
          function tag_push() {
          docker tag ${{ github.event.repository.name }} $IMAGE_ID:$1
          docker push $IMAGE_ID:$1
          }
          # Strip git ref prefix from version
          VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')
          # trigger is (hopefully semantically) tagged
          if [[ "${{ github.ref }}" == "refs/tags/"* ]]; then
            # Strip +buildinfo
            VERSION=$(cut -d+ -f1 <<< $VERSION)
            # Strip "v" prefix from tag name (v1.2.3 to 1.2.3)
            VERSION=$(sed -e 's/^v//' <<< $VERSION)
            
            if [[ -z $(cut -sd- -f1 <<< $VERSION) ]]; then # Not a prerelease (not v0.1.2-rc4)
              
              [[ ${TAG_LATEST} == "true" ]] && tag_push latest
              
              tag_push $VERSION # push patch (:1.2.3)
            
              # push minor version (:1.2)
              VERSION=$(cut -d. -f -2 <<< $VERSION)
              tag_push $VERSION
            
              # major version (:1)
              VERSION=$(cut -d. -f -1 <<< $VERSION)
            fi
          fi
          
          # push normally (and possibly major)
          tag_push $VERSION
          # Can't push multiple tags at once: https://github.com/docker/cli/issues/267