docker-publish.yml

name: Docker

on:
  push:
    # Publish `main` as Docker `latest` image.
    branches:
      - main
      - docker-publish

    # Publish `v1.2.3` tags as releases.
    tags:
      - v*

env:
  IMAGE_NAME: default

jobs:
  push:

    runs-on: ubuntu-latest
    if: github.event_name == 'push'

    steps:
      - uses: actions/checkout@v2

      - name: Build image
        run: docker build . --file Dockerfile --tag $IMAGE_NAME --cache-from ghcr.io/${{ github.repository }}:latest

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

      - name: Push image
        run: |
          IMAGE_ID=ghcr.io/${{ github.repository }}
          # Change all uppercase to lowercase
          IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')
          # Strip git ref prefix from version
          VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')
          # Strip "v" prefix from tag name
          [[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION | sed -e 's/^v//')
          # Use Docker `latest` tag convention
          [ "$VERSION" == "main" ] && VERSION=latest
          echo IMAGE_ID=$IMAGE_ID
          echo VERSION=$VERSION
          docker tag $IMAGE_NAME $IMAGE_ID:$VERSION
          docker push $IMAGE_ID:$VERSION