.github/workflows/changelog-build.yml

name: 'Changelog Build (Release)'

on:
  push:
    tags:
      - '*'

jobs:
  changelog:
    if: startsWith(github.ref, 'refs/tags/')
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
        with:
          fetch-depth: 0 # Required due to the way Git works, without it this action won't be able to find any or the correct tags

      - name: Get Previous tag
        id: previous_tag
        # git for-each-ref --sort=-creatordate --format '%(refname)' refs/tags ==> refs/tags/vX.Y.Z in descending order of date
        # awk 'FNR == 2 {print substr($1, 11, length($1))}') ==> Selects the 2nd tag from the list, then strips the /refs/tags/ part of the tag
        # set-output name=tag_name:: ==> Takes the clean tag vX.Y.Z and sets it to steps.previous_tag.outputs.tag_name
        run: |
          echo "::set-output name=tag_name::$(git for-each-ref --sort=-creatordate --format '%(refname)' refs/tags | awk 'FNR == 2 {print substr($1, 11, length($1))}')"
          echo ${{ steps.previous_tag.outputs.tag_name }}

      - name: Build Changelog
        id: github_tag
        uses: mikepenz/release-changelog-builder-action@v3.3.1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          # Configuration file is setup with filters for domains
          # owner:repo must point to current repo
          # fromTag: Auto resolved from historical tag order (previous tag compared to current tag)
          # toTag: Current tag reference
          configuration: ".github/workflows/config/changelog-config.json"
          owner: "NVIDIA"
          repo: "NeMo"
          ignorePreReleases: "false"
          failOnError: "false"
          fromTag: ${{ steps.previous_tag.outputs.tag_name }}
          toTag: ${{ github.ref_name }}

      - name: Print Changelog
        run: |
          echo "${{steps.github_tag.outputs.changelog}}"
          echo "--- DONE ---"