update-from-template.yml

name: Update from Template

# This workflow keeps the repo up to date with changes from the template repo (REMOTE_URL)
# It duplicates the REMOTE_BRANCH (into UPDATE_BRANCH) and tries to merge it into 
# this repos default branch (which is checked out here)
# Note that this requires a PAT (Personal Access Token) - at best from a servicing account
# PAT permissions: read:discussion, read:org, repo, workflow
# Also note that you should have at least once merged the template repo into the current repo manually
# otherwise a "refusing to merge unrelated histories" error might occur.

on:
  schedule:
    - cron: '55 2 * * 1'
  workflow_dispatch:
    inputs:
      no_automatic_merge:
        type: boolean
        description: 'No automatic merge'
        default: false

env:
  UPDATE_BRANCH: update-from-template
  UPDATE_BRANCH_MERGED: update-from-template-merged
  REMOTE_URL: https://github.com/xdev-software/standard-maven-template.git
  REMOTE_BRANCH: master

permissions:
  contents: write
  pull-requests: write

jobs:
  update:
    runs-on: ubuntu-latest
    outputs:
      update_branch_merged_commit: ${{ steps.manage-branches.outputs.update_branch_merged_commit }}
      create_update_branch_merged_pr: ${{ steps.manage-branches.outputs.create_update_branch_merged_pr }}
    steps:
      - uses: actions/checkout@v4
        with:
          # Required because otherwise there are always changes detected when executing diff/rev-list
          fetch-depth: 0
          # If no PAT is used the following error occurs on a push:
          # refusing to allow a GitHub App to create or update workflow `.github/workflows/xxx.yml` without `workflows` permission
          token: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
      
      - name: Init Git
        run: |
          git config --global user.email "111048771+xdev-gh-bot@users.noreply.github.com"
          git config --global user.name "XDEV Bot"

      - name: Manage branches
        id: manage-branches
        run: |
          echo "Adding remote template-repo"
          git remote add template ${{ env.REMOTE_URL }}
          
          echo "Fetching remote template repo"
          git fetch template
          
          echo "Deleting local branches that will contain the updates - if present"
          git branch -D ${{ env.UPDATE_BRANCH }} || true
          git branch -D ${{ env.UPDATE_BRANCH_MERGED }} || true
          
          echo "Checking if the remote template repo has new commits"
          git rev-list ..template/${{ env.REMOTE_BRANCH }}

          if [ $(git rev-list --count ..template/${{ env.REMOTE_BRANCH }}) -eq 0 ]; then
            echo "There are no commits new commits on the template repo"
            
            echo "Deleting origin branch(es) that contain the updates - if present"
            git push -f origin --delete ${{ env.UPDATE_BRANCH }} || true
            git push -f origin --delete ${{ env.UPDATE_BRANCH_MERGED }} || true
            
            echo "create_update_branch_pr=0" >> $GITHUB_OUTPUT
            echo "create_update_branch_merged_pr=0" >> $GITHUB_OUTPUT
            exit 0
          fi
          
          echo "Found new commits on the template repo"
          
          echo "Creating update branch"
          git branch ${{ env.UPDATE_BRANCH }} template/${{ env.REMOTE_BRANCH }}
          git branch --unset-upstream ${{ env.UPDATE_BRANCH }}
          
          echo "Pushing update branch"
          git push -f -u origin ${{ env.UPDATE_BRANCH }}
          
          echo "Getting base branch"
          base_branch=$(git branch --show-current)
          echo "Base branch is $base_branch"
          echo "base_branch=$base_branch" >> $GITHUB_OUTPUT

          echo "Trying to create auto-merged branch ${{ env.UPDATE_BRANCH_MERGED }}"
          git branch ${{ env.UPDATE_BRANCH_MERGED }} ${{ env.UPDATE_BRANCH }}
          git checkout ${{ env.UPDATE_BRANCH_MERGED }}
          
          echo "Merging branch $base_branch into ${{ env.UPDATE_BRANCH_MERGED }}"
          git merge $base_branch && merge_exit_code=$? || merge_exit_code=$?
          if [ $merge_exit_code -ne 0 ]; then
              echo "Auto merge failed! Manual merge required"
              echo "::notice ::Auto merge failed - Manual merge required"

              echo "Cleaning up failed merge"
              git merge --abort
              git checkout $base_branch
              git branch -D ${{ env.UPDATE_BRANCH_MERGED }} || true

              echo "Deleting auto-merge branch - if present"
              git push -f origin --delete ${{ env.UPDATE_BRANCH_MERGED }} || true

              echo "create_update_branch_pr=1" >> $GITHUB_OUTPUT
              echo "create_update_branch_merged_pr=0" >> $GITHUB_OUTPUT
              exit 0
          fi

          echo "Post processing: Trying to automatically fill in template variables"
          find . -type f \
            -not -path "./.git/**" \
            -not -path "./.github/workflows/update-from-template.yml" -print0 \
            | xargs -0 sed -i "s/template-placeholder/${GITHUB_REPOSITORY#*/}/g"

          git status
          git add --all

          if [[ "$(git status --porcelain)" != "" ]]; then
            echo "Filled in template; Committing"

            git commit -m "Fill in template"
          fi

          echo "Pushing auto-merged branch"
          git push -f -u origin ${{ env.UPDATE_BRANCH_MERGED }}

          echo "update_branch_merged_commit=$(git rev-parse HEAD)" >> $GITHUB_OUTPUT

          echo "Restoring base branch $base_branch"
          git checkout $base_branch

          echo "create_update_branch_pr=0" >> $GITHUB_OUTPUT
          echo "create_update_branch_merged_pr=1" >> $GITHUB_OUTPUT
          echo "try_close_update_branch_pr=1" >> $GITHUB_OUTPUT
          
      - name: Create/Update PR update_branch
        if: steps.manage-branches.outputs.create_update_branch_pr == 1
        env:
          GH_TOKEN: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
        run: |
          gh_pr_up() { 
            gh pr create -H "${{ env.UPDATE_BRANCH }}" "$@" || (git checkout "${{ env.UPDATE_BRANCH }}" && gh pr edit "$@")
          }
          gh_pr_up -B "${{ steps.manage-branches.outputs.base_branch }}" \
            --title "Update from template" \
            --body "An automated PR to sync changes from the template into this repo"
      
      # Ensure that only a single PR is open (otherwise confusion and spam)
      - name: Close PR update_branch
        if: steps.manage-branches.outputs.try_close_update_branch_pr == 1
        env:
          GH_TOKEN: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
        run: |
          gh pr close "${{ env.UPDATE_BRANCH }}" || true

      - name: Create/Update PR update_branch_merged
        if: steps.manage-branches.outputs.create_update_branch_merged_pr == 1
        env:
          GH_TOKEN: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
        run: |
          gh_pr_up() { 
            gh pr create -H "${{ env.UPDATE_BRANCH_MERGED }}" "$@" || (git checkout "${{ env.UPDATE_BRANCH_MERGED }}" && gh pr edit "$@")
          }
          gh_pr_up -B "${{ steps.manage-branches.outputs.base_branch }}" \
            --title "Update from template (auto-merged)" \
            --body "An automated PR to sync changes from the template into this repo"
          
          # Wait a moment so that checks of PR have higher prio than following job
          sleep 3

  # Split into two jobs to help with executor starvation
  auto-merge:
    needs: [update]
    if: needs.update.outputs.create_update_branch_merged_pr == 1
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          # Required because otherwise there are always changes detected when executing diff/rev-list
          fetch-depth: 0
          # If no PAT is used the following error occurs on a push:
          # refusing to allow a GitHub App to create or update workflow `.github/workflows/xxx.yml` without `workflows` permission
          token: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
      
      - name: Init Git
        run: |
          git config --global user.email "111048771+xdev-gh-bot@users.noreply.github.com"
          git config --global user.name "XDEV Bot"

      - name: Checking if auto-merge for PR update_branch_merged can be done
        id: auto-merge-check
        env:
          GH_TOKEN: ${{ secrets.UPDATE_FROM_TEMPLATE_PAT }}
        run: |
          not_failed_conclusion="skipped|neutral|success"
          not_relevant_app_slug="dependabot|github-pages|sonarcloud"

          echo "Waiting for checks to start..."
          sleep 40s

          for i in {1..20}; do
            echo "Checking if PR can be auto-merged. Try: $i"

            echo "Checking if update-branch-merged exists"
            git fetch
            if [[ $(git rev-parse origin/${{ env.UPDATE_BRANCH_MERGED }}) ]]; then
              echo "Branch still exists; Continuing..."
            else
              echo "Branch origin/${{ env.UPDATE_BRANCH_MERGED }} is missing"
              exit 0
            fi

            echo "Fetching checks"
            cs_response=$(curl -sL \
              --fail-with-body \
              --connect-timeout 60 \
              --max-time 120 \
              -H "Accept: application/vnd.github+json" \
              -H "Authorization: Bearer $GH_TOKEN" \
              -H "X-GitHub-Api-Version: 2022-11-28" \
              https://api.github.com/repos/${{ github.repository }}/commits/${{ needs.update.outputs.update_branch_merged_commit }}/check-suites)
            
            cs_data=$(echo $cs_response | jq '.check_suites[] | { conclusion: .conclusion, slug: .app.slug, check_runs_url: .check_runs_url }')
            echo $cs_data

            if [[ -z "$cs_data" ]]; then
              echo "No check suite data - Assuming that there are no checks to run"

              echo "perform=1" >> $GITHUB_OUTPUT
              exit 0
            fi

            cs_failed=$(echo $cs_data | jq --arg x "$not_failed_conclusion" 'select ((.conclusion == null or (.conclusion | test($x))) | not)')
            if [[ -z "$cs_failed" ]]; then
              echo "No check failed so far; Checking if relevant checks are still running"

              cs_relevant_still_running=$(echo $cs_data | jq --arg x "$not_relevant_app_slug" 'select (.conclusion == null and (.slug | test($x) | not))')
              if [[ -z $cs_relevant_still_running ]]; then
                echo "All relevant checks finished - PR can be merged"

                echo "perform=1" >> $GITHUB_OUTPUT
                exit 0
              else
                echo "Relevant checks are still running"
                echo $cs_relevant_still_running
              fi
            else
              echo "Detected failed check"
              echo $cs_failed

              echo "perform=0" >> $GITHUB_OUTPUT
              exit 0
            fi

            echo "Waiting before next run..."
            sleep 30s
          done

          echo "Timed out - Assuming executor starvation - Forcing merge"
          echo "perform=1" >> $GITHUB_OUTPUT
      
      - name: Auto-merge update_branch_merged
        if: steps.auto-merge-check.outputs.perform == 1
        run: |
          echo "Getting base branch"
          base_branch=$(git branch --show-current)
          echo "Base branch is $base_branch"

          echo "Fetching..."
          git fetch
          if [[ $(git rev-parse origin/${{ env.UPDATE_BRANCH_MERGED }}) ]]; then
            echo "Branch still exists; Continuing..."
          else
            echo "Branch origin/${{ env.UPDATE_BRANCH_MERGED }} is missing"
            exit 0
          fi

          expected_commit="${{ needs.update.outputs.update_branch_merged_commit }}"
          actual_commit=$(git rev-parse origin/${{ env.UPDATE_BRANCH_MERGED }})
          if [[ "$expected_commit" != "$actual_commit" ]]; then
            echo "Branch ${{ env.UPDATE_BRANCH_MERGED }} contains unexpected commit $actual_commit"
            echo "Expected: $expected_commit"

            exit 0
          fi

          echo "Ensuring that current branch $base_branch is up-to-date"
          git pull

          echo "Merging origin/${{ env.UPDATE_BRANCH_MERGED }} into $base_branch"
          git merge origin/${{ env.UPDATE_BRANCH_MERGED }} && merge_exit_code=$? || merge_exit_code=$?
          if [ $merge_exit_code -ne 0 ]; then
            echo "Unexpected merge failure $merge_exit_code - Requires manual resolution"

            exit 0
          fi

          if [[ "${{ inputs.no_automatic_merge }}" == "true" ]]; then
            echo "Exiting due no_automatic_merge"

            exit 0
          fi

          echo "Pushing"
          git push

          echo "Cleaning up"
          git branch -D ${{ env.UPDATE_BRANCH }} || true
          git branch -D ${{ env.UPDATE_BRANCH_MERGED }} || true
          git push -f origin --delete ${{ env.UPDATE_BRANCH }} || true
          git push -f origin --delete ${{ env.UPDATE_BRANCH_MERGED }} || true