Docker with GitHub Actions

docker-example.yml

  
name: Publish Docker image

on:
  push:
    branches:
    - master
    paths:
    - 'docker-example/*'
    - '.github/workflows/docker-example.yml'

jobs:
  build:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v1

    - name: Build and tag image
      run: docker build -t "docker.pkg.github.com/$GITHUB_REPOSITORY/docker-example:$GITHUB_SHA" -f docker-example/Dockerfile .

    - name: Docker login
      run: docker login docker.pkg.github.com -u $GITHUB_ACTOR -p $GITHUB_TOKEN
      env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

    - name: Publish to GPR
      run: docker push "docker.pkg.github.com/$GITHUB_REPOSITORY/docker-example:$GITHUB_SHA"

Given a repository with the structure

/ 
  .github/
    workflows/
      docker-example.yml
  docker-example/
    Dockerfile