Instructions/compatibility with GitHub Actions

[magneticflux-]

Now that GitHub Actions is in beta and more people are getting access to it, it makes sense to broaden the compatible CI environments for ShipKit.

[aepfli]

Just an fyi, we (https://github.com/junit-pioneer/junit-pioneer) migrated now from travis to github actions. it is working with some "hacks".

1. shipkit relies on the environment variable TRAVIS_BRANCH to work successfully, but this can be easily injected
2. github.ref which contains the branch contains it with refs/head/ in the beginning, which cause troubles and needs to be split

our deploy action look like

deploy:
    needs: build
    runs-on: ubuntu-latest
    name: Deploy with Shipkit
    if: github.ref == 'refs/heads/master'
    steps:
      - name: Sanitize Branch
        uses: frabert/replace-string-action@master
        id: gitbranch
        with:
          pattern: 'refs/heads/(.*)'
          string: "${{ github.ref }}"
          replace-with: '$1'
      - uses: actions/checkout@v2
      - name: Setup java
        uses: actions/setup-java@v1
        with:
          java-version: 8
      - name: Perform Release
        uses: eskatos/gradle-command-action@v1
        env:
          TRAVIS_BRANCH: ${{ steps.gitbranch.outputs.replaced }}
          TRAVIS_COMMIT_MESSAGE: ${{ github.event.head_commit.message }}
          TRAVIS_PULL_REQUEST: ${{ github.event_name == 'pull_request' }}
          GH_WRITE_TOKEN: ${{ secrets.GH_WRITE_TOKEN }}
          BINTRAY_USER_NAME: ${{ secrets.BINTRAY_USER_NAME }}
          BINTRAY_API_KEY: ${{ secrets.BINTRAY_API_KEY }}
          NEXUS_TOKEN_USERNAME: ${{ secrets.NEXUS_TOKEN_USERNAME }}
          NEXUS_TOKEN_PASSWORD: ${{ secrets.NEXUS_TOKEN_PASSWORD }}
        with:
          arguments: ciPerformRelease

and in our shipkit.gradle we added some parameters so that CI is correctly linked.

see junit-pioneer/junit-pioneer#199

[mstachniuk]

I created an example project for that issue: https://github.com/mstachniuk/shipkit-gh-actions-example

It's a little bit complicated but works better in case of setting TRAVIS_BRANCH for Pull Request build.
Using just TRAVIS_BRANCH: ${{ steps.gitbranch.outputs.replaced }} sets it to refs/pull/7/merge but Travis sets it to the real PR source branch.

Because of https://github.com/mockito/shipkit/blob/master/docs/design-specs/future-shipkit.md
there is no plan yet (nor volunteers) to support GitHub Actions and other CI systems. Instead, we started extracting the most important features to the separates plugins, e.g.: https://github.com/shipkit/shipkit-auto-version & https://github.com/shipkit/shipkit-changelog . Those plugins should have more configurations options. Someday Shipkit will use those plugins (hopefully).