auto-pr-from-main-into-releases.yml

name: PR changes on main into release branches
env:
    SOURCE_BRANCH: main
on:
  # This workflow should trigger when changes are pushed to main.
  # We expect this will happen when PRs into main are merged and also as
  # part of the automated bugfix release process.
  push:
    branches:
      # The context variable ${{ env.SOURCE_BRANCH }} does not seem to work here.
      - main

jobs:
  create-pr:
    # Only create a PR from main into release branches if we're on the
    # main invest repository.
    if: github.repository == 'natcap/invest'
    name: PR main into release/**
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - run: git fetch origin +refs/tags/*:refs/tags/*

      # Needed for envsubst
      - run: sudo apt-get update && sudo apt-get install gettext-base

      - name: Open a PR into each open release branch
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          SOURCE_BRANCH: ${{ env.SOURCE_BRANCH }}
        run: |
          set -x

          # Get the number of the last PR merged into main.
          # This assumes that the default PR message was used and includes
          # the pattern #[1-9][0-9]*.
          PR_NUM=$(git log -1 --pretty=%B main | head -n1 | egrep -o '#[1-9][0-9]*' | sed 's|#||g')

          # Get the username of the person who opened up the last PR into `main`.
          PR_USERNAME=$(gh pr view --json author $PR_NUM | jq -j '.author.login')
          echo "Latest PR on main ($PR_NUM) was authored by $PR_USERNAME."

          if [ "$PR_USERNAME" = "github-actions" ]
          then
              # Set the PR reviewer/assignee to the release manager.
              source ./ci/release/RELEASE_MANAGER.env
              PR_USERNAME=$RELEASE_MANAGER
          fi

          # Using grep with pattern ^release filters out any autorelease branches.
          # If no release branches are found, exit github actions.
          BRANCHES=$(git ls-remote --heads origin | cut -d '/' -f 3- | grep ^release || echo '')
          if [ -z "$BRANCHES" ]
          then
              echo "No release branches found; exiting github actions workflow."
              exit 0
          fi

          echo $BRANCHES  # debugging
          ERRORSPRESENT=0
          for BRANCH in $BRANCHES
          do
              export RELEASE_BRANCH=$BRANCH  # needed for envsubst
              PR_BODY_FILE=pr_body.txt
              cat ci/main-release-pr-body.md | envsubst > $PR_BODY_FILE
              cat $PR_BODY_FILE  # for debugging

              # This PR will be assigned to $GITHUB_ACTOR, which should be
              # the person who merged the PR that caused this commit to be
              # created.  Others could of course be assigned later.
              gh pr create \
                  --head $SOURCE_BRANCH \
                  --base $RELEASE_BRANCH \
                  --reviewer "$PR_USERNAME" \
                  --assignee "$PR_USERNAME" \
                  --label "auto" \
                  --title "auto merge main into release/*" \
                  --body-file $PR_BODY_FILE || ERRORSPRESENT=$(($ERRORSPRESENT | $?))
          done

          if [[ $ERRORSPRESENT -gt 0 ]]
          then
              echo "At least one of the PRs failed and might need to be revisited."
              exit 1
          fi