branch-rename.yml

name: Deprecate "master" branch
on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master

jobs:
  on-push:
    runs-on: ubuntu-latest
    if: ${{ github.event_name == 'push' }}
    steps:
      - name: Deprecation
        uses: peter-evans/commit-comment@v1
        with:
          body: |
            Hello @${{ github.event.sender.login }}!

            I see that you have pushed some commits to the "master" branch. We are in the process of renaming the "master" branch to "main" in this repository.

            :warning: **The "master" branch is deprecated and will be removed from this repository in the future.**

            Please migrate your local repository by renaming the "master" branch to "main":

            ```bash
            $ cd my-git-project
            $ git checkout master
            $ git branch -m main
            $ git branch -u origin/main
            ```

            Before merging pull requests, ensure their base branch is set to "main" instead of "master". For more information on how to do this, refer to [this GitHub support article][1].

            [1]: https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/changing-the-base-branch-of-a-pull-request

  on-pull-request:
    runs-on: ubuntu-latest
    if: ${{ github.event_name == 'pull_request' }}
    env:
      DEPRECATION_MESSAGE: |
        Hello @${{ github.event.sender.login }}!

        I see that you have opened a pull request against the "master" branch. We are in the process of renaming the "master" branch to "main" in this repository.

        :warning: **The "master" branch is deprecated and will be removed from this repository in the future.**

        Please migrate your local repository by renaming the "master" branch to "main":

        ```bash
        $ cd my-git-project
        $ git checkout master
        $ git branch -m main
        $ git branch -u origin/main
        ```

        Please also set the base branch for this pull request to "main" instead of "master". For more information on how to do this, refer to [this GitHub support article][1].

        [1]: https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/changing-the-base-branch-of-a-pull-request
    steps:
      - name: Deprecation
        if: ${{ github.event.pull_request.head.repo.fork == false }}
        uses: peter-evans/create-or-update-comment@v1
        with:
          issue-number: ${{ github.event.number }}
          body: ${{ env.DEPRECATION_MESSAGE }}
      - name: Deprecation
        if: ${{ github.event.pull_request.head.repo.fork == true }}
        run: |
          echo "$DEPRECATION_MESSAGE"
          echo '::error::Please set the base branch for this pull request to "main" instead of "master".'
          exit 1