No support for Python packages versioning (PEP 440)

Hi!

Thanks for the cool action! It works like a charm …as long as you are using semver.

Unfortunately in my case I wanted to use it for a Python package, which is versioned according to a pythonic standard - PEP440 - which is not semver-compatible.

I couldn’t just use type=match as in the case of the pre-release versions we should not add any other tags than the one with just the version itself.

Initially I wanted to create a PR to add support for PEP 440 to this project, but I don’t really know Typescript, so I ended up with writing it in, well, Python.

I would like to share this solution here for other people with such problem to find it and use this as a workaround and/or for someone to consider rewriting this in Typescript and making that PR. 😃

Anyway: happy hacking!

name: publish 🐳 Docker image

on:
  push:
    tags:
      - "v*"

jobs:

  build-and-push-image:

    runs-on: ubuntu-latest

    permissions:
      contents: read
      packages: write

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

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1

      - name: Login to GitHub Container Registry
        uses: docker/login-action@v1
        with:
          registry: ghcr.io
          username: ${{ github.repository_owner }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Get tags
        shell: python
        run: |
          import re
          from packaging.version import parse

          version = "${{ github.ref }}".replace("refs/tags/v", "")
          image = "ghcr.io/${{ github.repository }}"

          tags = set()

          # full version
          tags.add(f"{image}:{version}")

          if not parse(version).is_prerelease:
              # only final and post-releases should get the tags
              # used for automatic use of latest *stable* version

              # major_version
              major_version = re.search(r'(\d+?)\.', version).group(1)
              tags.add(f"{image}:{major_version}")

              # major_version.minor_version
              major_and_minor_version = re.search(r'(\d+?\.\d+?)\.', version).group(1)
              tags.add(f"{image}:{major_and_minor_version}")

              tags.add(f"{image}:latest")

          tags = ",".join(sorted(list(tags)))

          print(f"::set-output name=tags::{tags}")

        id: tags

      - name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          platforms: linux/amd64
          push: true
          tags: ${{ steps.tags.outputs.tags }}

(source: https://github.com/voxpupuli/puppetboard/commit/924bb55f02d06a4bcc1fd326449503170b412c97 + https://github.com/voxpupuli/puppetboard/commit/94052a0330b1e73963504a2a2fff9dbab52b2a87)

[crazy-max]

@gdubicki @tillsteinbach You can test the type=pep440 with crazy-max/docker-metadata-action@pep440. Doc: https://github.com/crazy-max/docker-metadata-action/tree/pep440#typepep440

[tillsteinbach]

Ahrg! Yes, I was unconcentrated 😃 really nice work! Interestingly I did not notice my mistake because PyPi did the same correction to my version number 😄