Question 190288 in Ubuntu Question posted in
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Ubuntu – Running Github Action to keep a branch up-to-date with main

We have a test environment that runs on the test branch, I would like to run an Github Action that keeps test up to date when pushes are made to main, but I just cant seem to get it. When I run the code through the CLI, it works, but when I run the action, it does not work…

name: Update Test Branch

on:
  push:
    branches: [main]


jobs:
  sync:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
        
      - name: Setup Git User
        run: |
          git config user.name "GitHub Action"
          git config user.email "<EMAIL>"
      

      - name: Update Test Branch
        run: |
          git fetch origin
          git checkout test
          git pull
          git merge --allow-unrelated-histories origin/main
          git push origin test

At first, I got fatal: refusing to merge unrelated histories, so I added the –allow-unrelated-histories tag. Now, I get an error indicating some merge conflict. However, the error does not throw when I run the commands manually.

There have never been any manual commits to the test. It has only and always should depend on main, meaning it should always have a related history. There may be future exceptions to this, but we have yet to reach this.

Please help me understand what I am doing wrong!

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Expanding on @jessehouwing 's helpful comment, the checkout step needs to be a full checkout. Additionally, I had to configure my action to have write access to the repository. The complete implementation of the action is as follows:

    name: Update Test Branch

on:
  push:
    branches: [main]
    
permissions: write-all

jobs:
  sync:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Setup Git User
        run: |
          git config user.name "GitHub Action"
          git config user.email "<EMAIL>"

      - name: Update Test Branch
        run: |
          git checkout main
          git fetch origin
          git checkout test
          git pull
          git merge --allow-unrelated-histories origin/main
          git push origin test

    Thank you Jesse, if you would like to make a complete answer, I can accept yours.


  2. 0

    Because the GitHub Actions Runner performs a shallow clone for performance reasons, the full history isn’t available on the runner when you try to do the merge. This is what causes the error about "unrelated histories".

    To solve this, you’ll want to add fetch-depth: 0 to the checkout step:

          - name: Checkout
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

    That should remove the need for --allow-unrelated-histories in your commit block:

          - name: Update Test Branch
        run: |
          git checkout main
          git fetch origin
          git checkout test
          git pull
          git merge origin/main
          git push origin test

    Finally, you’ll need to add the permissions to push back to the repo, the new defaults are that your runner will be configured with read-only permissions. Granting contents: write should suffice here. And it’s best to provide the minimum set required from, a security perspective:

    permissions:
    contents: write

    Which ends up with the following workflow:

    name: Update Test Branch

on:
  push:
    branches: [main]
    
permissions: 
  contents: write

jobs:
  sync:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Setup Git User
        run: |
          git config user.name "GitHub Action"
          git config user.email "<EMAIL>"

      - name: Update Test Branch
        run: |
          git checkout main
          git fetch origin
          git checkout test
          git pull
          git merge origin/main
          git push origin test
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