Upmerge Action

A GitHub Action that creates upmerge PRs between branches when there are changes to merge.

Usage

name: Upmerge PR

on:
    schedule:
        - cron: "0 2 * * *"
    workflow_dispatch: ~

permissions:
    contents: write
    pull-requests: write

jobs:
    upmerge:
        runs-on: ubuntu-latest
        strategy:
            fail-fast: false
            matrix:
                include:
                    - base_branch: "1.0"
                      target_branch: "1.1"
                    - base_branch: "1.1"
                      target_branch: "1.2"

        steps:
            - uses: actions/checkout@v4
              with:
                  ref: ${{ matrix.target_branch }}

            - uses: SyliusLabs/UpmergeAction@v1
              with:
                  base_branch: ${{ matrix.base_branch }}
                  target_branch: ${{ matrix.target_branch }}
                  token: ${{ secrets.GITHUB_TOKEN }}

Inputs

Input	Required	Description
base_branch	Yes	Source branch to upmerge from (e.g., 1.0)
target_branch	Yes	Target branch to upmerge to (e.g., 1.1)
token	Yes	GitHub token with permissions to create PRs

Outputs

Output	Description
created	Whether a PR was created (true or false)
pr_number	PR number if created, empty otherwise
pr_url	PR URL if created, empty otherwise

Behavior

• Creates a PR from upmerge/{base}_{target} branch to merge changes from base to target
• If target already contains all changes from base, succeeds without creating a PR
• If an upmerge branch was manually modified (e.g. conflict resolution), it is preserved — the action skips to avoid overwriting work
• Unmodified upmerge branches are recreated with the latest base to keep them fresh
• Uses gh CLI for PR creation (no external action dependencies)