merge_ff_only.yml

name: Merge (ff only)
on:
  workflow_dispatch:
  workflow_call:
    inputs:
        source-repo:
          required: true
          type: string
          description: Source repo path in the format [REPO_OWNER]/[REPO_NAME]
        target-repo:
          required: true
          type: string
          description: Target repo path in the format [REPO_OWNER]/[REPO_NAME]
        source-branch:
          required: true
          type: string
          description: Source branch from [SOURCE_REPO] that you want merged into [TARGET_BRANCH] from [TARGET_REPO]
        target-branch:
          required: true
          type: string
          description: Target branch to merge [SOURCE_BRANCH] from [SOURCE_REPO] into.
        env-name:
          required: false
          type: string
          description: Github environment name that your github token secret is in
    secrets:
        github-token:
          required: true
jobs:
  Promote:
    environment: ${{ inputs.env-name }}
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
      with:
          repository: ${{ inputs.source-repo }}
          ref: ${{ inputs.source-branch }}
          persist-credentials: false
          fetch-depth: 0
    - name: Merge source-branch into target-branch
      env:
          # gh needs this env var set with the exact name GH_TOKEN
          GH_TOKEN: ${{ secrets.github-token }}
          SOURCE_BRANCH: ${{ inputs.source-branch }}
          TARGET_BRANCH: ${{ inputs.target-branch }}
          TARGET_REPO: ${{ inputs.target-repo }} 
      shell: bash
      run: |
        git config --global user.email "promote@github.com"
        git config --global user.name "auto-promote"
        git config --global --add --bool push.autoSetupRemote true
        git remote add target-repo "https://$GH_TOKEN@github.com/$TARGET_REPO.git"
        git fetch -q target-repo
        git branch --track "$TARGET_BRANCH-target-repo" remotes/target-repo/$TARGET_BRANCH
        echo "After tracking target branch external"
        git switch -q "$TARGET_BRANCH-target-repo"
       
        git merge $SOURCE_BRANCH --ff-only
        git push -q target-repo HEAD:$TARGET_BRANCH