Example workflow used in this article: https://medium.com/@merlin.pav/122c653c0b09?source=friends_link&sk=4ca7d4ab89ce41f2118a1d9aad50807d

github_article_sample_cd_workflow__setenvs.yaml

deployment:
    name: Deploy backend to cluster
    runs-on: 'ubuntu-latest'
    needs: [docker-image]
    steps:
    - name: Checkout working branch
      uses: actions/checkout@v1

    - name: Set Release version
      run: |
        echo ::set-env name=RELEASE_VERSION::$(echo ${GITHUB_REF} | 
                            sed -e "s/refs\/tags\///g" | sed -e "s/\//-/g")

    - name: Cluster env for production
      if: "!github.event.release.prerelease"
      run: |
        echo ::set-env name=CLUSTER_ENV::prod

    - name: Cluster env for staging/dev
      if: "github.event.release.prerelease"
      run: |
        BRANCH=$(git branch -r --contains ${GITHUB_SHA} | grep "")
        MASTER_BRANCH_NAME='origin/master'

        if [[ "$BRANCH" == *"$MASTER_BRANCH_NAME"* ]]; then
          echo ::set-env name=CLUSTER_ENV::stag
        else
          echo ::set-env name=CLUSTER_ENV::dev
        fi

    - name: Set Cluster credentials
      run: |
        echo ::set-env name=CLUSTER_NAME::acme-gke-${{ env.CLUSTER_ENV }}
        echo ::set-env name=CLUSTER_ZONE::europe-west3-a
        echo ::set-env name=PROJECT_NAME::acme-555555