close_issue_on_pr_merge.yml

name: Close Issues on PR Merge

on:
  pull_request:
    types: [closed]

jobs:
  close-issues:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout repository
      uses: actions/checkout@v2

    - name: Close linked issues
      if: github.event.pull_request.merged == true
      run: |
        ISSUES=$(jq -r '.pull_request.body' "$GITHUB_EVENT_PATH" | grep -Eo '#[0-9]+' | tr -d '#')
        for ISSUE in $ISSUES
        do
          echo "Closing issue #$ISSUE"
          curl -X POST -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
               -H "Accept: application/vnd.github.v3+json" \
               https://api.github.com/repos/${{ github.repository }}/issues/$ISSUE/comments \
               -d '{"body":"Closed by PR #${{ github.event.pull_request.number }}"}'
          curl -X PATCH -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
               -H "Accept: application/vnd.github.v3+json" \
               https://api.github.com/repos/${{ github.repository }}/issues/$ISSUE \
               -d '{"state":"closed"}'
        done