hugo-updates.yml

on:
  schedule:
    # * is a special character in YAML so you have to quote this string
    - cron:  '0 12 1 * *'

name: hugo-update

jobs:  
  hugo-update:
    name: hugo-update
    runs-on: ubuntu-latest

    steps:    
    - uses: actions/checkout@v2
      
    - name: Assess update need
      # Get currently used Hugo version from netlify.toml -- needs to be HUGO_VERSION = "blabla" with spaces
      # Get latest Hugo version from GitHub API
      # Compare both
      run: |
          ov=$(grep 'HUGO_VERSION' netlify.toml -m 1 | grep -o -P '(?<=HUGO\_VERSION[[:space:]]\=[[:space:]]\").*(?=\")')
          nv=$(curl --request GET \
          --url https://api.github.com/repos/gohugoio/hugo/releases/latest \
          --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' \
          | jq --raw-output .name)
          nv=${nv#v}
          needupdate=false
          if [ $ov != $nv ]
            then
              needupdate=true
              echo "Hugo needs to be updated"
            else
              echo "Hugo already up-to-date! :-)"
          fi
          echo "::set-env name=needupdate::$needupdate"
          echo "::set-env name=ov::$ov"
          echo "::set-env name=nv::$nv"
      # Now if needed, update by editing netlify.toml,
      # Creating a branch and the corresponding PR
    - name: Updating
      if: env.needupdate == 'true'
      run: |
          git config --global user.email "example@example.com"
          git config --global user.name "gh-pages committer"
          git checkout -b "hugo-update${{ env.nv }}"
          sedp="s/HUGO_VERSION\s=\s\"${{ env.ov }}\"/HUGO_VERSION \= \"${{ env.nv }}\"/g" 
          sed -i "$sedp" netlify.toml
          git commit netlify.toml -m 'Update Hugo' || echo "No changes to commit"
          git push --set-upstream origin "hugo-update${{ env.nv }}"
          head="${{ github.repository_owner }}:hugo-update${{ env.nv }}"
          docsurl="https://gohugo.io/news/${{ env.nv }}-relnotes/"
          # https://stackoverflow.com/questions/17029902/using-curl-post-with-variables-defined-in-bash-script-functions
          generate_pr_data()
          {
          cat <<EOF
          {
          "title": "Update Hugo to ${{ env.nv }}",
          "body": "Hugo needs to be updated. :rocket: \n [Release notes for Hugo ${{ env.nv }}]($docsurl).",
          "head": "$head",
          "base": "master"
          }
          EOF
          }
          echo "$(generate_pr_data)" 
          curl --request POST \
          --url https://api.github.com/repos/${{ github.repository }}/pulls \
          --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' \
          --data "$(generate_pr_data)"