branch-guard.yml

# if the base_ref(target branch we want to merge to) is master and the head_ref(source branch we want to merge from)
# Then throw an error, as only release is allowed to merge into master
# Otherwise this action won't run and show as success
name: 'Branch guard 🛡️'

on:
  pull_request:
    types: [opened, edited, synchronize]

jobs:
  can-merge-to-branch:
    name: Can merge to branch
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Checking if branch is allowed...
        if: "github.base_ref == 'master' && github.head_ref != 'release'"
        run: |
          echo "";
          echo "::error::Not allowed to merge '$GITHUB_HEAD_REF' branch into '$GITHUB_BASE_REF' branch";
          echo "---";
          exit 1;